The US Supreme Court recently heard the death penalty case of Hall v. Florida. One of the key issues in the case was the margin of error for the IQ test administered to Mr. Hall. In the test in question Hall registered as having an IQ of 71 (although a prior test result was registered as 60.) The liberal justices joined by Justice Kennedy questions the margin of error for the test and whether a person should be executed because of registering at 71, when the cut-off for life in prison was 70. The margin of error for the test in dispute is said to be 5 points. Observers believe that, in these circumstances, the court is unlikely to let the execution proceed.
This issue of the sensitivity and accuracy of testing and expert witness testimony with a known or unknown margin of error can be a vexing one for expert witnesses.
The court’s ruling in Hall v. Florida may open Pandora’s box on this margin of error and expert witness testimony. Attorney and expert witnesses will want to read the court’s decision carefully and prepare for the inevitable increase in margin of error questions for expert witnesses.