Junk Science

Overview 

The term ​“junk sci­ence” gained par­tic­u­lar sig­nif­i­cance in crim­i­nal law dur­ing the late 1980s and ear­ly 1990s, as courts began grap­pling with the reli­a­bil­i­ty of var­i­ous foren­sic tech­niques. Attorney and writer Peter Huber pop­u­lar­ized the term in his 1991 book Galileo’s Revenge: Junk Science in the Courtroom, which described grow­ing con­cerns about the sci­en­tif­ic valid­i­ty of tech­niques used to ana­lyze and test evi­dence that crim­i­nal courts had long accept­ed. Traditional foren­sic tech­niques, like hair microscopy and bite mark analy­sis, as well as aspects of fin­ger­print exam­i­na­tion came under greater scruti­ny as advances in DNA test­ing and tech­nol­o­gy demon­strat­ed the poten­tial for more rig­or­ous stan­dards in foren­sic analy­sis. Today, the term ​“junk sci­ence” encom­pass­es a vari­ety of evi­dence types that have been proven to be scientifically unreliable. 

The recog­ni­tion of ​“junk sci­ence” in crim­i­nal courts led to reforms in the legal sys­tem’s approach to sci­en­tif­ic evi­dence. The United States Supreme Court’s deci­sion in Daubert v. Merrell Dow Pharmaceuticals (1993) estab­lished a new stan­dard for the admis­si­bil­i­ty of expert tes­ti­mo­ny dur­ing tri­al, requir­ing judges to act as ​“gate­keep­ers” in eval­u­at­ing the valid­i­ty of sci­en­tif­ic evi­dence. This marked a depar­ture from the pre­vi­ous­ly estab­lished Frye stan­dard, which sim­ply required gen­er­al accep­tance of infor­ma­tion with­in the rel­e­vant sci­en­tif­ic com­mu­ni­ty. Although the appli­ca­tion of Daubert has var­ied across juris­dic­tions, it has gen­er­al­ly led to height­ened scruti­ny of forensic techniques. 

More recent years have seen con­tin­ued evo­lu­tion in how courts and attor­neys address potential ​“junk sci­ence” evi­dence in crim­i­nal cas­es. The 2016 President’s Council of Advisors on Science and Technology (PCAST) report placed a spot­light on the lim­i­ta­tions of cer­tain foren­sic tech­niques, lead­ing some juris­dic­tions to restrict or elim­i­nate the use of tech­niques pre­vi­ous­ly con­sid­ered reli­able. A 2023 National Institute of Justice (NIJ) study found that sys­tem­at­ic errors in more than 30 foren­sic dis­ci­plines have played roles in wrong­ful con­vic­tions, broad­ly. Today’s courts increas­ing­ly rec­og­nize that sci­en­tif­ic knowl­edge is not sta­t­ic, and what constitutes ​“junk sci­ence” may change as under­stand­ing deep­ens, and ana­lyt­i­cal capabilities grow. 

At Issue 

The impact of ques­tion­able foren­sic sci­ence tech­niques on wrong­ful con­vic­tions became increas­ing­ly appar­ent through the work of orga­ni­za­tions like the Innocence Project, estab­lished in 1992. Post-con­vic­­tion DNA test­ing con­firmed that defen­dants had been wrong­ful­ly con­vict­ed based on foren­sic evi­dence that was lat­er shown to be unre­li­able or improp­er­ly inter­pret­ed. Issues with ​“junk sci­ence” have sur­faced in many cap­i­tal cas­es, and in con­junc­tion with oth­er issues, such as offi­cial mis­con­duct, has been cit­ed as fac­tors in at least 65 death row exonerations.