STUDIES — Junk Psychological Science Continues to Infect Death-Penalty Determinations

Courts are fail­ing bad­ly in keep­ing junk psy­cho­log­i­cal sci­ence out of the court­room in crim­i­nal cas­es, per­mit­ting the admis­sion of psy­cho­log­i­cal tests that have nev­er been reviewed for reli­a­bil­i­ty and oth­ers that have been found unre­li­able, a recent study reports. Among the prob­lem­at­ic tests, anoth­er group of psy­chol­o­gists write, is a ​“psy­chopa­thy check­list” com­mon­ly used by pros­e­cu­tors to argue that a defen­dant pos­es a future dan­ger to soci­ety and should be sen­tenced to death.

The arti­cle, Psychological Assessments in Legal Contexts: Are Courts Keeping ​“Junk Science” Out of the Courtroom?, which was pub­lished February 15, 2020 in the Association of Psychological Science jour­nal, Psychological Science in the Public Interest, looked at 364 psy­cho­log­i­cal assess­ment tools psy­chol­o­gists report­ed hav­ing used in legal cas­es. It found that near­ly a quar­ter of the tests were con­sid­ered unre­li­able, one-third lacked gen­er­al accep­tance in the field of psy­chol­o­gy, ​“and only about 40% ha[d] gen­er­al­ly favor­able reviews of their psy­cho­me­t­ric and tech­ni­cal prop­er­ties.” Yet, the researchers wrote, legal chal­lenges to the tests were raised in only 5.1% of the 876 state and fed­er­al cas­es reviewed in which the evi­dence was pre­sent­ed, and those chal­lenges failed about two-thirds of the time. 

“There’s a lot of stuff that looks like it’s junk and should be fil­tered out by the courts, but it’s not being fil­tered out,” said Arizona State University psy­chol­o­gy pro­fes­sor Tess Neal, the lead author of the study.

One con­tro­ver­sial psy­cho­log­i­cal test, the Hare Psychopathy Checklist — Revised (PCL – R), came under fire in the American Psychological Association’s jour­nal, Psychology, Public Policy, and Law. In a joint state­ment first pub­lished on-line on January 30, 2020, thir­teen expert psy­chi­a­trists and psy­chol­o­gists wrote that while the test may have gen­er­al use­ful­ness in mea­sur­ing psy­chopa­thy ​“as a con­struct,” it is ​“inap­pro­pri­ate [to use] the PCL – R to draw con­clu­sions about an individual’s risk for com­mit­ting seri­ous vio­lence in high-secu­ri­ty cus­to­di­al facil­i­ties.” Such con­clu­sions are often crit­i­cal in cap­i­tal sen­tenc­ing deter­mi­na­tions in states such as Texas in which find­ing that a defen­dant pos­es a con­tin­u­ing threat to soci­ety is a pre­req­ui­site to impos­ing a death sentence. 

The experts crit­i­cize the PCL – R as plagued by adver­sar­i­al alle­giance — men­tal health wit­ness­es called by the pros­e­cu­tion will rate a defendant’s lev­el of psy­chopa­thy high­er than defense experts will dur­ing ​“eval­u­a­tions of the same per­son, made around the same time, and even when made on the same infor­ma­tion base.” They also say that ​“the asso­ci­a­tion between PCL – R scores and seri­ous insti­tu­tion­al vio­lence is neg­li­gi­ble,” mak­ing the test unre­li­able as an indi­ca­tor of whether a defen­dant will actu­al­ly com­mit vio­lence in prison. The PCL – R ​“can­not make pre­dic­tions that an indi­vid­ual will engage in seri­ous insti­tu­tion­al vio­lence with any rea­son­able degree of pre­ci­sion or accu­ra­cy,” they say, ​“and should not be used for this pur­pose in cap­i­tal sentencing evaluations.”

Experts in psy­chol­o­gy have long argued that pre­dic­tions of future dan­ger­ous­ness are junk sci­ence, and their use in cap­i­tal sen­tenc­ing pro­ceed­ings con­tin­ues to cre­ate seri­ous con­sti­tu­tion­al con­cerns. On February 22, 2017, the U.S. Supreme Court over­turned the death sen­tence imposed in Texas on Duane Buck, whose tri­al was taint­ed by racial bias when the defense’s own psy­chol­o­gist tes­ti­fied that Buck posed a future dan­ger because he was black. On August 19, 2016, the Texas Court of Criminal Appeals stayed the exe­cu­tion of Jeffery Wood to per­mit him to lit­i­gate claims that the future dan­ger­ous­ness pre­dic­tions of the state’s expert — who had been expelled from state and nation­al pro­fes­sion­al asso­ci­a­tions for his unsci­en­tif­ic and uneth­i­cal future dan­ger­ous­ness pre­dic­tions in the past — con­sti­tut­ed false sci­en­tif­ic evi­dence whose use vio­lat­ed due process.