Foren­sic Sci­ence “Matches”-The Case of Black Powder

By:  Fred­eric White­hurst, J.D., Ph.D. [1]

While review­ing case opin­ions in crim­i­nal mat­ters involv­ing foren­sic exam­i­na­tions one is often pre­sented with var­i­ous adjec­tives of com­par­i­son such as “matches,” “con­sis­tent with,” and “iden­ti­cal to.” Coun­sel see­ing these adjec­tives in foren­sic reports may be elated if legal the­o­ries are sup­ported or dis­turbed if not. How­ever, one way or the other, there is a wealth of infor­ma­tion behind these adjec­tives which may go unex­plored and if brought up dur­ing trial can leave pros­e­cu­tors defend­ing new ground dur­ing lit­i­ga­tion and defense coun­sel scor­ing impor­tant points in dis­cred­it­ing prof­fered expert tes­ti­mony. One should be drawn to ques­tion whether these words are an indi­ca­tion that data has been over-inferred by the expert offer­ing them. One is also drawn to ask, if fol­low­ing Giglio², the infor­ma­tion behind these words should have been pre­sented as pos­si­ble excul­pa­tory infor­ma­tion to unsus­pect­ing pros­e­cu­tors before trial. Com­par­i­son adjec­tives left dan­gling alone to describe the results of com­par­isons may not prop­erly edu­cate the trier-of-fact to the true sig­nif­i­cance of the data. And more impor­tantly, the true sig­nif­i­cance of the data may not be known by the foren­sic sci­en­tist. For exam­ple Jon­akait³ tells us that “The con­clu­sions of foren­sic sci­ence are often based on skimpy, nonex­is­tent, or shoddy research. Foren­sic sci­en­tists do not give juries a thor­ough pre­sen­ta­tion of infor­ma­tion about the sci­en­tific technique.”

This paper will address the adjec­tive “matches” as an exam­ple point­ing out the very wide door of oppor­tu­nity it opens for future prob­ing dur­ing exam­i­na­tion. The adjec­tives, if not prop­erly sup­ported by empir­i­cal data, can offer coun­sel the oppor­tu­nity to point out to the trier-of-fact what may be a flawed opin­ion, pos­si­bly even a “foren­sic scam” being per­pe­trated upon the court through the hid­ing of excul­pa­tory infor­ma­tion. This paper will also explore the Giglio oblig­a­tion of the prosecution’s foren­sic sci­en­tists to reveal the empir­i­cal data or lack thereof and their total under­stand­ing of the data to full view.

The world of man-made prod­ucts is com­posed of com­plex mate­ri­als con­structed with many com­po­nents each with its own man­u­fac­tur­ing sig­na­ture. When the foren­sic expert tes­ti­fies that two com­plex mate­ri­als “match,” coun­sel is encour­aged to ask of what the mate­ri­als are com­posed, which of the com­po­nents match, how the expert has deter­mined this, what com­po­nents were not and/or can not be detected with the analyst’s tools and the impli­ca­tions of not being able to deter­mine if these com­po­nents matched or not. As an ini­tial exam­ple we will look at a very sim­ple and very old man-made mate­r­ial, black pow­der, an explosive.

Black Pow­der

Though the ori­gins of black pow­der are debated, it was the major explo­sive used in war­fare, firearms and indus­tries such as min­ing until the late 1800’s. The black grains of mate­r­ial are com­posed of potas­sium nitrate, sul­fur and char­coal. Black pow­der has been pro­duced essen­tially in the same man­ner for hun­dreds of years. At first glance it appears to be a sim­ple mate­r­ial of three com­po­nents. How­ever a closer “hard look” reveals a fas­ci­nat­ingly com­plex mate­r­ial of many, many pos­si­ble sub­com­po­nents and phys­i­cal char­ac­ter­is­tics. The expert wit­ness who opines that two black pow­ders “match” then can be asked to explain what about the mate­ri­als is it that matches … and what is the sig­nif­i­cance of that match. Let us explore the world of infor­ma­tion behind the word “match” when it is applied to two black pow­der samples.

We may ask first who man­u­fac­tures the com­po­nents of black pow­der. This knowl­edge allows us to check prof­fered expert opin­ions against actual man­u­fac­tur­ers’ under­stand­ings of their own prod­ucts. We can eas­ily deter­mine the man­u­fac­tur­ers of a mate­r­ial and ask a num­ber of ques­tions. How is potas­sium nitrate man­u­fac­tured? How is sul­fur man­u­fac­tured? How is char­coal man­u­fac­tured? What are the raw prod­ucts that go into the man­u­fac­ture of these mate­ri­als and what chem­i­cal and phys­i­cal sig­na­tures do they carry with them to the final black pow­der mix­ture. What are the var­i­ous grades of these mate­ri­als and what grades are uti­lized in the man­u­fac­ture of black pow­der? What pos­si­ble minor impu­ri­ties are found in these com­po­nents that might change the types of black pow­der in minor but impor­tant ways? Who man­u­fac­tures black pow­der itself? How much of the mate­r­ial is man­u­fac­tured? What are the phys­i­cal char­ac­ter­is­tics of black pow­der? What grades of black pow­der are man­u­fac­tured? The expert who is pre­pared under oath to ren­der the bare opin­ion that black pow­der spec­i­mens “match” should surely have con­sid­ered these ques­tions at length and have ready answers, data and the sci­en­tific lit­er­a­ture to sup­port his opinion.

Potas­sium Nitrate

A quick trip to the chem­istry library to look into the Ency­clo­pe­dia of Chem­i­cal Tech­nol­ogy⁴ tells us that “Potas­sium nitrate, which was essen­tial in the man­u­fac­ture of black gun­pow­der, was pro­duced cen­turies ago by the Chi­nese.… The process involved leach­ing soil in which nitro­gen from urine had com­bined with min­eral potas­sium. By the time of the Napoleonic wars, potas­sium nitrate was a strate­gic chem­i­cal and was still obtained in the same man­ner, pri­mar­ily from India.” One can cer­tainly imag­ine that if potas­sium nitrate were still man­u­fac­tured in this man­ner it would carry a lot of impu­ri­ties out of the soil with it. How­ever we are not to be treated to such a sim­ple answer.

We find from the same ref­er­ence⁵ that “Most of the potas­sium nitrate, KNO3, pro­duced com­mer­cially in the United States is based on the reac­tion of potas­sium chlo­ride and nitric acid.” So here we have two other mate­ri­als the ori­gins and purity of which we must con­sider. We are advised of the fol­low­ing com­po­si­tion of potas­sium chlo­ride⁶:

One can see that with all of these mate­ri­als in the potas­sium chlo­ride used in the man­u­fac­ture of potas­sium nitrate, their occur­rence in the potas­sium nitrate derived in part from the potas­sium chlo­ride is pos­si­ble. Indeed ref­er­ence to the cer­tifi­cate of analy­sis on a bot­tle of a Fisher Cer­ti­fied Reagent grade potas­sium nitrate from lot num­ber 745536 found in the lab­o­ra­tory in which the author works notes the fol­low­ing impu­ri­ties: Com­po­nent Guar­an­teed Com­po­si­tion wt % Fe (iron) .0001% Heavy met­als (as lead) .0001% SO4 (sul­fate) .001% Na (sodium) .005% Insol­u­ble mat­ter .001% Cl (Chorine total) .002% PO4 (phos­phate) .0001% Ca + Mg .002%

As small as the per­cent­ages are they are still mea­sur­able and have obvi­ously been mea­sured in the assay of this reagent grade mate­r­ial. Coun­sel should not have to accept the opin­ion that the mate­ri­als are not present in suf­fi­cient quan­tity to mea­sure and are there­fore not impor­tant to estab­lish­ing a match. That kind of state­ment should be backed up with empir­i­cal data, data that indi­cates that minor com­po­nents do not change sig­nif­i­cantly between batches or grades of black pow­der. What does “sig­nif­i­cantly” mean? That is another ques­tion for the expert to answer.

Sul­fur

We read in the Ency­clo­pe­dia of Chem­i­cal Tech­nol­ogy⁷ that “Sul­fur has been known since antiq­uity.… One con­tem­po­rary use was devel­oped in 500 BC, when the Chi­nese used sul­fur as an ingre­di­ent of gun­pow­der.” And fur­ther we read that⁸ “Sul­fur occurs in a num­ber of dif­fer­ent allotropic mod­i­fi­ca­tions, that is, in var­i­ous mol­e­c­u­lar aggre­ga­tions which dif­fer in sol­u­bil­ity, spe­cific grav­ity, crys­talline form, etc. Like many other sub­stances, sul­fur also exhibits dynamic allotropy, ie. the var­i­ous allotropes exist together in equi­lib­rium in def­i­nite pro­por­tions, depend­ing on the tem­per­a­ture and pres­sure.… The par­tic­u­lar allotropes that may be present in a given sam­ple of sul­fur depend to a large extent upon its pre­vi­ous ther­mal his­tory, the amount and type of for­eign sub­stance present, and the length of time that has passed for equi­lib­rium to be attained.”

These are state­ments full of the won­der­ful poten­tial for explo­ration. There is men­tion of impu­ri­ties. What impu­ri­ties exist in sul­fur? An expert in a par­tic­u­lar type of mate­r­ial might rea­son­ably be expected to have con­sid­ered this ques­tion in the past just as he might have been expected to con­sider the impu­ri­ties in potas­sium nitrate. After all, if an expert is going to say that the chem­i­cal com­po­si­tion of two mate­ri­als such as black pow­der match, then he can rea­son­ably be expected to have some under­stand­ing of what those chem­i­cal com­po­si­tions are. And then we can ask what allotropes are present in the sul­fur that is in the black pow­der. Inter­est­ingly the ency­clo­pe­dia⁹ notes the many grades of sul­fur as fol­lows: amor­phous sul­fur, bright sul­fur, brim­stone, bro­ken rock sul­fur, bro­ken sul­fur, col­loidal sul­fur, crude sul­fur, dark sul­fur, dust­ing sul­fur, ele­men­tal sul­fur, flour sul­fur, flow­able sul­fur, flow­ers of sul­fur, Frasch sul­fur, insol­u­ble sul­fur, lac sul­fur, liq­uid sul­fur, molten sul­fur, native sul­fur, pre­cip­i­tated sul­fur, prilled sul­fur, recov­ered sul­fur, refined sul­fur, roll sul­fur, rubbermaker’s sul­fur, run-of-mine sul­fur, screened com­mer­cial sul­fur, slated sul­fur, spe­cialty sul­furs and wet­table sul­fur. Now who would imag­ine that sul­fur could come in so many forms? Dare we ask if the dif­fer­ent forms might have dif­fer­ent impu­rity sig­na­tures? An expert who pro­fesses to know that two black pow­der sam­ples “match” with­out describ­ing those char­ac­ter­is­tics that match might be inclined to have asked and to have answered that ques­tion. Or pos­si­bly the “match” did not include con­sid­er­a­tion of trace impurities.

Char­coal

The most impres­sive com­plex com­po­nent of black pow­der is the char­coal. It is this com­po­nent that con­tains the great­est wealth of oppor­tu­nity for exam­i­na­tion, both legal and sci­en­tific. The Hand­book of Char­coal Mak­ing¹⁰ defines char­coal as “The residue of solid non-agglomerating organic mat­ter, of veg­etable or ani­mal ori­gin, that results from car­boniza­tion by heat in the absence of air at a tem­per­a­ture above 300 degrees centigrade.”

The def­i­n­i­tions also include those of charcoal’s com­po­nents as fol­lows¹¹:

1.)“Content of Volatiles: If char­coal is heated to 900 degrees under con­fined con­di­tions, it will lose weight because hydro­car­bons and nitro­gen are dri­ven out. This weight loss is extremely impor­tant to indus­trial char­coal con­sumers when defin­ing the uti­liza­tion properties.”

2.) “Ash con­tent: The ash is com­posed of the nat­ural min­er­als con­tained in almost any organic mat­ter and con­t­a­m­i­na­tions. The quan­tity is related to the com­po­si­tion of the raw mate­r­ial mix, e.g. wood branches with a high pro­por­tion of bark will give high ash con­tain­ing char­coal. Char­coal ashes are dis­tin­guished by their sol­u­bil­ity in water and by chem­i­cal analysis.”

3.) “Sul­phur and phos­pho­rus con­tent: The low sum of these sub­stances nor­mally found in char­coals makes them espe­cially attrac­tive for use in blast iron fur­naces and for met­al­lur­gi­cal purposes.”

4.) “Pyrol­y­sis Oil: The oil varies very much with the type of raw mate­r­ial. It con­tains more than one hun­dred dif­fer­ent sub­stances, which once made it a valu­able feed­stock for the chem­i­cal industry.”

With these def­i­n­i­tions we real­ize that char­coal could be con­sid­ered the most com­plex com­po­nent of black powder.

An impor­tant field of research in black pow­der char­coals has been con­ducted by mil­i­tary lab­o­ra­to­ries in attempts to bet­ter define the explo­sive power of this explo­sive.¹² Black pow­der is used to pro­pel mil­i­tary pro­jec­tiles. If the black pow­der is not well char­ac­ter­ized then high explo­sive rounds may fall on friendly lines or may not hit intended tar­gets. The work of Ronald Sasse et. al. for the U.S. Depart­ment of Defense is par­tic­u­larly instruc­tive in char­ac­ter­iz­ing black pow­der. In Sasse’s papers “Organic sub­sti­tutes for char­coal in ‘black pow­der’ type pyrotech­nic for­mu­la­tions¹³,” “Char­ac­ter­i­za­tion of maple char­coal used to make black pow­der¹⁴″ and “Char­ac­ter­i­za­tion of char­coal used to make black pow­der¹⁵,” we see a trea­sure of infor­ma­tion that can be explored by coun­sel. Char­coal used in black pow­der orig­i­nates from dif­fer­ent veg­etable sources. These sources invari­ably orig­i­nate from dif­fer­ent areas and there­fore nutri­ent envi­ron­ments. Each batch of char­coal is con­se­quently very likely dif­fer­ent. Even the man­u­fac­turer who uses the same type of tree for his char­coal uti­lizes trees that orig­i­nate from dif­fer­ent sources. These sources imprint their own nutri­ent and growth sig­na­ture on the char­coal product.

Expert tes­ti­mony that is offered that black pow­der sam­ples “match” should raise ques­tions con­cern­ing the chem­i­cal and phys­i­cal char­ac­ter­i­za­tion of the char­coals found in the black pow­der. Remem­ber­ing that char­coal par­ti­cles will have dif­fer­ent con­tents of organic and inor­ganic chem­i­cals as well as dif­fer­ent shapes and struc­tures, coun­sel can ask for the data that totally defines these char­ac­ter­is­tics. If they have not been defined then a dan­gling “match” must be bet­ter defined.

Black Pow­der, The Product

Black pow­der uti­lized in the United States orig­i­nates from a num­ber of sources. The largest of those sources is Goex, Inc.¹⁶ The GOEX black pow­der plant in Moosic, Penn­syl­va­nia, has been pro­duc­ing black pow­der since 1912. Kosanke¹⁷ advises that there are also sources of Chi­nese, Russ­ian, Brazil­ian and Scot­tish black pow­ders in the United States at this time as well as black pow­der which orig­i­nates from mil­i­tary sur­plus. A sim­ple review of the GOEX sales brochure notes that black pow­der comes as superfine black sport­ing pow­der, mil­i­tary pow­der, fire­works pow­der, blast­ing pow­der and com­mer­cial pow­der. Each of those head­ings has sub­classes. Under superfine black sport­ing pow­der one finds can­non, Fg, FFg, FFFg, FFFFg, and car­tridge pow­ders. Under mil­i­tary black pow­der one finds type Mil-P-223B pow­der fur­ther sub­di­vided into class 1 through class 8 and pro­pel­lant com­po­si­tion, type JAN-P-663A sub­di­vided into type I fuze and type II fuze pow­ders, and type JAN-P-362 pow­ders. Under fire­works pow­der one finds 1Fa through 7Fa, meal D, Fine meal, and extra fine meal. Under Blaster Pow­der one finds 1FBB, through 4FBB pow­der. Under com­mer­cial fuse pow­der one finds pow­ders with speeds of 85, 108, 111, 116, 124, 126, 132, 140 and 165 seconds/yard.

As the reader can see, these pow­ders, though all com­posed of potas­sium nitrate, sul­fur and char­coal may have dif­fer­ent char­ac­ter­is­tics. For instance, no two black pow­der gran­ules, which have the appear­ance of black­ened coarse grains of sand, are exactly alike in size and shape. Sasse and Rose can there­fore tells us that there is a size dis­tri­b­u­tion of these pow­der par­ti­cles in any one prod­uct type.¹⁸ Accord­ing to infor­ma­tion the author received from a rep­re­sen­ta­tive of GOEX, because of this size dis­tri­b­u­tion, par­ti­cles of one size may be found in more than one type of black pow­der. For exam­ple, par­ti­cles of a par­tic­u­lar size which are found in FFg may also be found in FFFg pow­der. There­fore while not­ing that par­ti­cles from two dif­fer­ent sources match in size the expert must also hon­estly put forth the infor­ma­tion that other sources of dif­fer­ent types of black pow­der are not excluded as pos­si­ble sources. It would also be help­ful to let coun­sel and the trier-of-fact know just how many other sources of a par­tic­u­lar type of black pow­der there were. This may be impos­si­ble as the black pow­der par­ti­cles frac­ture in the can¹⁹. Another prob­lem with black pow­der size com­par­i­son may very well be in com­par­ing unini­ti­ated black pow­der with black pow­der par­ti­cles found in residue from exploded impro­vised explo­sives devices. If pow­der can frac­ture in the can, one can be cer­tain that it will frac­ture when sub­jected to explo­sive forces.

Though quan­ti­ties of black pow­der that exist in the United States are not known accu­rately one can get an esti­mate from look­ing at black pow­der usage as well as the pub­lished sci­en­tific lit­er­a­ture on black pow­der. Jon Uithol, of the National Muz­zle Load­ing Rifle Asso­ci­a­tion²⁰ advises that there are three to seven mil­lion muz­zle load­ing state hunt­ing licenses issued per year in the U.S.. These firearms uti­lize black pow­der or a black pow­der sub­sti­tute called Pyrodex. Black pow­der is sold in small­est units of pounds. This would indi­cate that mil­lions of pounds of black pow­der presently exist in this coun­try as pur­chased prod­uct. Rose notes about black pow­der that “the civil­ian con­sump­tion alone must be more than a thou­sand met­ric tons annu­ally.“²¹

A Range of Choices

The Fed­eral Judi­cial Center’s Ref­er­ence Man­ual on Sci­en­tific Evi­dence²² asks the ques­tion “Have alter­na­tive expla­na­tions been ruled out?” explain­ing fur­ther that “Alter­na­tive expla­na­tions and con­found­ing fac­tors should be exam­ined and ruled out to avoid reach­ing an erro­neous con­clu­sion. How­ever, it is never pos­si­ble to rule out every alter­na­tive expla­na­tion.” Another source²³ describes Judge Wein­stein in Agent Orange²⁴, rec­og­niz­ing that unless research that seeks to estab­lish cau­sa­tion for one agent also takes into account other fac­tors that may explain the plaintiff’s injuries, the find­ing may improp­erly over­es­ti­mate cau­sa­tion. Because the evi­dence pre­sented failed to take into account fac­tors other than Agent Orange dioxin that could have caused the veteran’s ill­nesses, it was not sci­en­tif­i­cally valid, and Judge Wein­stein prop­erly excluded the evi­dence as legally unre­li­able.” This is very much on point here. Com­plex mate­ri­als and their com­po­nents are man­u­fac­tured in many forms with many uses, and with upper and lower lim­its of accep­tance of phys­i­cal and chem­i­cal char­ac­ter­is­tics. Those lim­its trans­late into prod­ucts hav­ing dif­fer­ent chem­i­cal and phys­i­cal char­ac­ter­is­tics even though pro­duced on the same pro­duc­tion lines for iden­ti­cal pur­poses. When those lim­its are very tight, dif­fer­ences are dif­fi­cult if not impos­si­ble to detect with mod­ern ana­lyt­i­cal tools. The result of this is that alter­na­tive expla­na­tions can not always be ruled out no mat­ter how thor­ough the analy­sis is.

In the case of black pow­der the man­u­fac­tur­ers upper and lower lim­its must be care­fully con­trolled so that the pow­der ini­ti­ates only upon com­mand and not spon­ta­neously, result­ing in unplanned dam­age and/or death. The range of dif­fer­ences in black pow­der do exist, how­ever, and pre­clude absolute matches.²⁵ The ana­lyst is com­pelled to deter­mine the lim­its of ranges and if pos­si­ble to deter­mine if sus­pect mate­ri­als fit within those ranges and there­fore could have orig­i­nated from the same sources. Ulti­mately, how­ever, the sci­en­tist reaches the point at which avail­able tech­nol­ogy can not assist in the fur­ther char­ac­ter­i­za­tion of mate­ri­als. At that point the legal sys­tem must deter­mine if the sci­en­tist should be com­pelled to report that fail­ure as a sci­en­tist and the sig­nif­i­cance of that fail­ure in light of what alter­na­tive expla­na­tions for the data can not be ruled out. Appar­ently Judge Wein­stein would sug­gest that alter­na­tive expla­na­tions that can not be ruled out should be pre­sented as evidence.

Giglio v. United States

One would assume that a pros­e­cu­tor would want to know the weak­nesses of opin­ions pre­sented by foren­sic experts if for no other rea­son than to avoid prob­lem­atic rev­e­la­tions dur­ing tes­ti­mony on cross exam­i­na­tion. But does the foren­sic sci­en­tist have a duty to present his total under­stand­ing of data or just that part that gives strength to the prosecutor’s the­ory of guilt?

One approach to the report­ing of the lim­i­ta­tions of sci­en­tific pro­to­cols is that estab­lished under Giglio. It is strange that a foren­sic sci­en­tist would even have to con­sider the law in deal­ing with the com­plete­ness of his reports. One would hope that there would be no taint of bias, that the sci­en­tific opin­ions would be ren­dered objec­tively. How­ever as noted in the British case Regina v. Judith Theresa Ward²⁶, “the dis­clo­sure of sci­en­tific evi­dence was woe­fully defi­cient. Three senior RARDE sci­en­tists took the law into their own hands, and con­cealed from the pros­e­cu­tion, the defence and the court, mat­ters which might have changed the course of the trial.” Foren­sic sci­en­tists do at times take the law into their own hands and become par­ti­san. There­fore guid­ance in the report­ing of the sig­nif­i­cance of foren­sic evi­dence might be necessary.

We are taught in “The Prosecutor’s Duty of Dis­close: From Brady to Agurs and Beyond“²⁷ that Giglio and prog­eny estab­lish that “Gen­er­ally a pros­e­cu­tor ‘should know’ of a piece of evi­dence if it is in his pos­ses­sion or in the pos­ses­sion of any agency involved in the pros­e­cu­tion.” Other agen­cies can include other pros­e­cu­tors in the office²⁸, law enforce­ment offi­cers²⁹, and any other inves­tiga­tive agen­cies involved in crim­i­nal pros­e­cu­tion³⁰. This would nat­u­rally include gov­ern­ment foren­sic lab­o­ra­to­ries. And in foot­note 130 of this arti­cle, quot­ing U.S v. McCord³¹, “The pros­e­cu­tion involves all agen­cies of the fed­eral gov­ern­ment involved in any way in the pros­e­cu­tion of crim­i­nal lit­i­ga­tion.” Giglio and prog­eny estab­lish that fail­ure to present excul­pa­tory infor­ma­tion is not excused as a result of the pros­e­cu­tor hav­ing no per­sonal knowl­edge of such infor­ma­tion while mem­bers of the agency assist­ing in the pros­e­cu­tion do have such knowl­edge. What does this say for foren­sic sci­en­tists who present their find­ings as “matches” with­out describ­ing the under­ly­ing mean­ing of the adjec­tive? Do these sci­en­tists have an oblig­a­tion to present the under­ly­ing mean­ing of the data that estab­lishes the match? If the matches are not absolute should the level of uncer­tainty be exposed to the pros­e­cu­tor? If the level of uncer­tainty is unknown should that also be reported to the pros­e­cu­tor? If foren­sic sci­en­tists are not will­ing to report the sig­nif­i­cance of their data objec­tively then how can the pros­e­cu­tor decide if Brady mate­r­ial and a Giglio oblig­a­tion exist as a result of sci­en­tific investigations?

What oblig­a­tion does the pros­e­cu­tor have to pro­vide pos­si­bly excul­pa­tory foren­sic infor­ma­tion. Agurs³² teaches that:

“Although there is, of course, no duty to pro­vide defense coun­sel with unlim­ited dis­cov­ery of every­thing known by the pros­e­cu­tor, if the sub­ject mat­ter of such a request is mate­r­ial, or indeed if a sub­stan­tial basis for claim­ing mate­ri­al­ity exists, it is rea­son­able to require the pros­e­cu­tor to respond either by fur­nish­ing the infor­ma­tion or by sub­mit­ting the prob­lem to the trial judge. When the pros­e­cu­tor receives a spe­cific and rel­e­vant request, the fail­ure to make any response is sel­dom, if ever excusable.”

But how does defense make spe­cific requests about com­plex sci­en­tific infor­ma­tion which may be excul­pa­tory in nature, may prove or be favor­able to estab­lish­ing inno­cence? The “match­ing” of com­plex foren­sic sam­ples is gen­er­ally not a skill that is employed out­side the government’s own lab­o­ra­to­ries. How can defense coun­sel even know to ask about the mor­pho­log­i­cal struc­ture of the char­coal in black pow­der sam­ples or the volatile organic com­pounds, or the pyrol­y­sis oils, or the impu­rity con­tent of potas­sium nitrate or the size dis­tri­b­u­tion char­ac­ter­is­tics of par­tic­u­lar types of black pow­der? Gen­er­ally nei­ther pros­e­cu­tion nor defense coun­sel have appro­pri­ate back­grounds to delve into or under­stand this type of information.

Agurs³³ iden­ti­fied this sit­u­a­tion in describ­ing the prosecution’s fail­ure to dis­close allegedly favor­able evi­dence that the defense had not specif­i­cally requested. This fail­ure could be inex­cus­able under Giglio and yet the pros­e­cu­tor, defense and court never pick up on the fail­ure when foren­sic evi­dence is con­cealed. One can imag­ine tes­ti­mony that estab­lished that two black pow­der sam­ples “matched” and yet the “match” was only in qual­i­ta­tive con­tent of potas­sium nitrate, sul­fur and char­coal. A trier-of-fact could wrongly infer from this tes­ti­mony that both black pow­der sam­ples had unique char­ac­ter­is­tics that set them apart from all the other hun­dreds of thou­sands, pos­si­bly mil­lions of pounds of black pow­der in exis­tence in the United States. With­out explain­ing the mean­ing and lim­i­ta­tions of “match” and with­out the pros­e­cu­tor or defense coun­sel being able to see through the prob­lem, the trier of fact might not be able to place the proper weight on evi­dence and injus­tice might result.

What evi­dence would be con­sid­ered excul­pa­tory? It would not take a great leap of faith to believe that if black pow­der were found at a crime scene and at a defendant’s res­i­dence that the defen­dant would argue that there are thou­sands of tons of black pow­der avail­able and in the hands of the Amer­i­can pub­lic and that the black pow­der found at the crime scene did not orig­i­nate from the defendant’s black pow­der. The expert who opined sim­ply that the two black pow­ders “matched” could very well mis­lead the trier of fact into believ­ing that the two sam­ples of black pow­der orig­i­nated from the same source. That expert would be con­ceal­ing evi­dence that very well could be con­sid­ered to be excul­pa­tory. One can also imag­ine the trier-of-fact who has been led by the expert to believe that two black pow­der sam­ples which “match” most likely orig­i­nated from the same source. Under these cir­cum­stances, any infor­ma­tion which revealed the lim­ited weight of that evi­dence could be con­sid­ered favor­able to the defense. Such evi­dence, if unsuc­cess­fully con­cealed, might even lead jurors to ques­tion the cred­i­bil­ity of the prof­fered expert. Imag­ine the trier-of-fact who has been led to believe through the “dan­gling adjec­tive of com­par­i­son” that two sam­ples orig­i­nated from the same source. Imag­ine now the effect on that same trier­of-fact when she learns that there are thou­sands if not mil­lions of sources of the same mate­r­ial, that the ana­lyst can not, in real­ity, deter­mine if the two mate­ri­als are chem­i­cally and phys­i­cally iden­ti­cal, and that the ana­lyst did not present that infor­ma­tion in his report or in his testimony.

Solu­tions

Coun­sel should look behind the adjec­tives of com­par­i­son, demand­ing to know what they mean. Foren­sic sci­en­tists should report their full under­stand­ing of the mean­ing of the com­par­i­son adjec­tives, remem­ber­ing that the oath is to “Tell the truth, the whole truth, and noth­ing but the truth.” A list of pos­si­bly use­ful exploratory ques­tions is pre­sented as a guide, using black pow­der as an example:

1.) What is black pow­der com­posed of? 2.) What ana­lyt­i­cal tech­niques were used to deter­mine the com­po­si­tion of these pieces of evi­dence? 3.) What infor­ma­tion about the com­po­nents did each of these instru­ments present? 4.) Are each of the mate­ri­als used in the man­u­fac­ture of black pow­der pure? 5.) If not, then did the instru­ments mea­sure the impu­ri­ties? 6.) If the instru­ments did not mea­sure the impu­ri­ties, how can one be sure that the black pow­ders “match.” 7.) What does “match” mean? 8.) If you can not mea­sure impu­ri­ties such as pyrol­y­sis oils, phos­pho­rous and sul­fur, and min­er­als in black pow­der par­ti­cles then how can you say that the par­ti­cles match with­out reveal­ing in what spe­cific ways they do match? 9.) Are all black pow­der par­ti­cles of the same size? 10.) If they are not of the same size, then what is the size dis­tri­b­u­tion of the par­ti­cles that you ana­lyzed and how did you mea­sure the dis­tri­b­u­tion? 11.) Was the black pow­der used in an impro­vised explo­sives device that exploded? 12.) Wouldn’t such an explo­sion break apart black pow­der par­ti­cles? 13.) If you say that it would not, please present your empir­i­cal data and results of your sci­en­tific analy­ses to show that an explo­sion would not frac­ture larger black pow­der par­ti­cles into smaller par­ti­cles. 14.) Did you con­duct a scan­ning elec­tron micro­scope com­par­i­son analy­sis of the mor­phol­ogy, size and shape, of the char­coal in the black pow­der par­ti­cles that you had as evi­dence. 15.) Did you deter­mine whether the black pow­der par­ti­cles that you had were man­u­fac­tured with char­coal from dif­fer­ent types of trees? 16.) If you did not, why didn’t you before you sim­ply said that the two pow­der sam­ples matched? 17.) Do you know what types of trees are used in the man­u­fac­ture of black pow­der par­ti­cles? If you do, then would you name them? 18.) Did you look for these dif­fer­ent types of wood char­coal? How do you rec­og­nize the dif­fer­ent char­coals? 19.) If you believe that the black pow­der par­ti­cles “match” and yet you have not mea­sured all the char­ac­ter­is­tics of the par­ti­cles, can you explain what is the basis for your say­ing that the par­ti­cles match? 20.) Can you explain why even though you were not able to and/or did not mea­sure some very impor­tant char­ac­ter­is­tics of the black pow­der par­ti­cles, you still wrote a lab­o­ra­tory report that said the black pow­der par­ti­cles matched and did not fur­ther explain the sig­nif­i­cance of the “match.”

Sum­mary

Adjec­tives of com­par­i­son such as “match,” ” con­sis­tent with” and “iden­ti­cal to” can be mis­lead­ing to triers-of-fact and can be used to prove almost any­thing. The expert wit­ness who opines that two mate­ri­als match opens the door very pos­si­bly to cross exam­i­na­tion which could be eas­ily used to dis­credit the wit­ness. Cross exam­i­na­tion can delve into the com­po­nents of the match­ing mate­ri­als, the instru­men­tal data from analy­ses of the mate­ri­als and into the basic sci­en­tific foun­da­tion for the opin­ion rendered.

We are left with a ques­tion as to whether Giglio oblig­a­tions of the pros­e­cu­tor require that the prosecutor’s experts reveal the basis for their use of com­par­i­son adjec­tives in their reports to the pros­e­cu­tor. These rev­e­la­tions would seem to be nec­es­sary in order that the pros­e­cu­tor be able to decide if infor­ma­tion held by mem­bers of his team was favor­able to the defense. Such infor­ma­tion would nor­mally be found in sci­en­tific reports from other dis­ci­plines and should not be left out of foren­sic reports.

_______________________

¹ Super­vi­sory Spe­cial Agent, Fed­eral Bureau of Inves­ti­ga­tion. Cur­rently assigned to the FBI Lab­o­ra­tory in Wash­ing­ton, D.C.. B.S., Chem­istry, 1974, East Car­olina Uni­ver­sity, Ph.D., Chem­istry, 1980, Duke Uni­ver­sity, J.D. 1996,Georgetown Uni­ver­sity School of Law.

The views expressed in this paper rep­re­sent those of the author and are not nec­es­sar­ily rep­re­sen­ta­tive of the views of the Fed­eral Bureau of Inves­ti­ga­tion, the United States Depart­ment of Jus­tice or the United States government.

² Giglio v. United States, 405 U.S. 150(1970).

³ Ran­dolph N. Jon­akait, Sto­ries, Foren­sic Sci­ence, andIm­proved Ver­dicts, 13 CARDOZO L. REV. 343, 349 (1991).

⁴ W.B.Dancy, Potas­sium Com­pounds, 18 ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY 920 (John Wiley & Sons, 1982).

⁵ Id. at 939.

⁶ Id. at 930.

⁷ D.W. Bixby, H.L. Fike, J.E. Shel­ton & T.K. Wiewiorowski,Sul­fur, 22 ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY 78 (John Wiley & Sons1982).

⁸ Id. at 79.

⁹ Id. at 97.

¹⁰ Wal­ter Emrich, HANDBOOK OF CHARCOAL MAKING 13 (D. Rei­delPub­lish­ing Co., 1985).

¹¹ Id. at 14, 17. 9

¹² R. Sasse, H. Homes, D. Hansen, W. Aungst, O. Doali, & R.Bowman, Eval­u­a­tion of Black Pow­der Pro­duced by the Indi­ana Army Ammu­ni­tion Plant, 11 PROC. INT. PYRO. SEMIN. 489, Tech­ni­cal Report, Bal­lis­tic Research Lab­o­ra­tory, Aberdeen Prov­ing Ground, Md.(1986).

¹³ S. Wise, R. A. Sasse, H.E. Homes, Organic Sub­sti­tutes for­Char­coal in ‘Black Pow­der’ Type Pyrotech­nic For­mu­la­tions, Tech­ni­cal Report, Bal­lis­tic Research Lab, Army Arma­ment Research and Devel­op­ment Cen­ter, Aberdeen Prov­ing Grounds, Md. (1984).

¹⁴ R.A. Sasse, Char­ac­ter­i­za­tion of Maple Char­coal Used To Make Black Pow­der, Bal­lis­tic Research Lab, Army Arma­ment Research Devel­op­ment Cen­ter, Aberdeen Prov­ing Ground, Md. (1983).

¹⁵ Sasse. R. A., Char­ac­ter­i­za­tion of Char­coal Used to Make Black Pow­der, 9 PROC. INT. PYROTECH. SEMIN. 471 (1984).

¹⁶ GOEX, Inc., Belin Plant, 1002 Spring­brook Ave. Moosic, Penn­syl­va­nia, 18507. Phone: (717) 457‑6724.

¹⁷ Dr. Ken­neth Kosanke, Edi­tor of Jour­nal of Pyrotechnics,1471 Blair Road, White­wa­ter, Col­orado, 81527, (970) 245‑0692.

¹⁸ R. Sasse & J.E. Rose, Com­par­i­son of Spher­i­cal and Ellip­soidal Form Func­tions for Eval­u­at­ing Black Pow­der, 13 PROC. INT. PYROTECH. SEMIN. 679 (1988).

¹⁹ John Uithol, Exec­u­tive Vice Pres­i­dent, National Muz­zle Load­ing Rifle Asso­ci­a­tion, Friend­ship, Indi­ana, (812) 667‑5131,advised the author in a pri­vate com­mu­ni­ca­tion that some black pow­der rifle enthu­si­asts wish greater repro­ducibil­ity of results in shoot­ing. They there­fore sieve pur­chased black pow­der to achieve a more uni­form par­ti­cle size. The siev­ing is required not only because of the size dis­tri­b­u­tion which orig­i­nates with the pur­chased prod­uct but also because of frac­ture in the can over time from jar­ring and dropping.

²⁰ Supra note 17.

²¹ J. E. Rose, Black Pow­der — A Mod­ern Com­men­tary — 1979, 10PROC. SYMP. EXPLOS. PYROTECH. 6a-1 (1979).

²² Fed­eral Judi­cial Cen­ter, REFERENCE MANUAL ON SCIENTIFIC EVIDENCE 163 (West Pub­lish­ing Co., 1993).

²³ Con­fronting the New Chal­lenges of Sci­en­tific Evi­dence,108 HARV. L. REV. 1481 1539 (1995).

²⁴ In re Agent Orange, 611 F.Supp. 1223 (E.D.N.Y. 1985), aff’d, 818 F.2d 187 (2d Cir.1987), cert. denied, 487 U.S. 1234(1988).

²⁶ Regina v. Judith Theresa Ward was heard in the Royal Courts of Jus­tice in the Court of Appeal, Crim­i­nal Divi­sion on June 4, 1992 before Lord Jus­tices Glidewell, Nolan and Steyn. The case is noto­ri­ous for its expo­sure of inap­pro­pri­ate foren­sic prac­tices by gov­ern­ment scientists.

²⁷ The Prosecutor’s Duty of Dis­close: From Brady to Agurs and Beyond, 69 J. CRIM. L. & CRIMINOLOGY 197 (1978).

²⁸ Giglio v. United States, 405 U.S. 150 (1972).

²⁹ Bar­bee v. War­den, Mary­land Pen­i­ten­tiary, 331 F.2d 842 (4th Cir. 1964).

³⁰ United States v. Eley, 335 F.Supp. 353 (N.D.Ga. 1972).

³¹ United States v. McCord, 509 F.2d 334 (D.C.Cir. 1974).

³² United States v. Agurs, 427 U.S. 97 (1976). 19

³³ Id. at 106.