In Connick v. Thompson, published March 29, 2011, the U.S. Supreme Court held 5-4 that a district attorney could not be held liable under a 42 U.S.C. section 1983 failure-to-train theory based on a deputy prosecutor's single instance of failing to turn potentially exculpatory evidence (a crime lab report stating the perpetrator's blood type, which was different than the suspect's blood type) over to the defense, as required by Brady v. Maryland (1963) 373 U.S. 83. The defense discovered the report only after the suspect had spent 18 years in prison, including 14 on death row, and a month before the suspect's scheduled execution.
The majority held that because the failure-to-train was governed by a deliberate-indifference standard, the D.A. could be held liable only if the D.A.'s office's policymakers are on actual or constructive notice that a particular omission in their training program is causing their employees to violate citizens' rights; and they make a deliberate choice to retain that program. Here, the plaintiff failed to show a pattern of failing to turn over this type of evidence based on an omission in the office's training on Brady. The court noted that past failure-to-train cases had held that a single constitutional violation that revealed an obvious omission in training might support liability. But, the court held, because lawyers are required to receive legal training, pass a bar exam, remain subject to professional discipline, and often must continue their legal education, policymakers may presume that they know the law concerning Brady well enough that a single omission would not support failure-to-train liability. The court emphasized that failure-to-train cases are particularly difficult to prove.
The dissent opined that the evidence showed a pattern of offenses that should have put the D.A. on notice of an omission in training prosecutors concerning their Brady obligations.