work from the past, and suggested that “galvano-psychic and vaso-motor reactions [would] be more delicate indicators than blood pressure; but the same results would be caused by so many different circumstances, anything demanding equal activity (intellectual or emotional), that it would be practically impossible to divide any individual case.” His report went on to suggest alterations in the experimental protocol to protect against suspected biases. Many of the problems cited are familiar to modern critics of the polygraph test.
At this point, Marston was also completing his law degree at Harvard, and his correspondence with Yerkes focused on seeking employment with the government, first the War Department and then the Department of Justice, in lieu of actual service in the armed forces. Marston appears to have been successful and secured a commission to carry out further work in the Sanitary Corps, where he completed research described initially in an unpublished report dated December 18, 1918, and subsequently published (Marston, 1921). According to Marston (1938), he and his colleagues tested a total of 100 criminal cases in Boston criminal court, and his systolic blood pressure test led to correct determinations in 97 of them (see Lykken, 1991). There are no further references to Marston’s work in the NRC files except for an inquiry in 1935 from J. Edgar Hoover, director of the Federal Bureau of Investigation. The NRC response referred Hoover to Marston’s publications (1917, 1920, 1921, 1925, and 1929). Both Marston (1938) and Bunn (1997) refer to his having used his test on spies during this period, but no details are available.
After World War I, Marston pursued an academic career, and he appeared as an expert witness in the now famous 1923 Frye case, in which the defense unsuccessfully attempted to introduce his expert testimony as to the innocence of the defendant on the basis of his systolic blood pressure test. According to Marston (1938), Frye was accused of murder in the District of Columbia and, after first denying all knowledge of the event, confessed and provided police with correct details of the killing. A few days later, Frye recanted the confession, claiming that he admitted to the crime because he had been promised a share of the reward for his own conviction. Marston then gave Frye his deception test in a D.C. jail and found his claim of innocence to be entirely truthful. When Marston was introduced as an expert witness at trial, the presiding judge excluded the evidence on the grounds that the test had been administered in jail 10 days before Frye testified in court and that it was irrelevant to the veracity of his testimony. Frye was convicted of murder (Frye v. United States, 293 F.1013 [D.C. Cir. 1923]). The case was appealed on the ground that the trial judge erroneously excluded Marston’s testimony. On appeal, the circuit court argued that the judge was correct in excluding the evidence: