Duty to Disclose or Act Upon Exculpatory Evidence

November 23, 2009

By: David K. Jaffe

Although there is no general duty to discovery evidence to exonerate a suspect, an action for malicious prosecution may lie when exculpatory evidence negating probable cause is not disclosed. Destruction of material, exculpatory evidence in bad faith is a deprivation of due process.

The parameters of common-law police liability for intentional or negligent failure to notify a suspect, his attorney, or the prosecutor of exculpatory or even exonerating evidence are unclear. Older cases [1] held that a sheriff's failure to quickly notify the suspect, his attorney, or the prosecutor that a blood test in a drunk-driving action showed the presence of no alcohol violated no duty was not actionable. The decision emphasized that neither suppression nor concealment of the results of the test had occurred. The delay in release caused by the routine forwarding of the information was two weeks.

Actions for false arrest and/or malicious prosecution may, however, be based upon an officer's intentional suppression of exculpatory evidence. There are substantial pitfalls since (a) probable cause may be present despite the suppression and (b) proximate cause may be lacking. Failure to discover obvious exculpatory evidence may at times negate probable cause in false-arrest and malicious prosecution actions.

Federal civil rights liability may be predicated upon intentional suppression of significant exculpatory evidence. The court in Lambert v. McFarland [2] held that a municipal practice of not informing the prosecutor or defense attorney of an exonerating drug report prior to the next scheduled hearing date was unconstitutional. The officer who received the information did not claim that he acted pursuant to the policy and was liable for false imprisonment.

More difficult are what may be called the delayed discovery or disclosure of exculpatory evidence situations where, as in Lambert, exonerating evidence is not immediately acted upon. In Pennington v. Hobson, [3] a field test of a substance found on an arrestee indicated the presence of cocaine, and he was detained pursuant to an arrest warrant. The substance was not sent to a state police laboratory for a month. A month later, it was determined to be aspirin. The plaintiff was released a month thereafter. Although negligent loss of the field test result (if such occurred) violated no clearly established law, and there was no right to a rapid laboratory confirmation, a right to release upon actual confirmation of innocence had been clearly established in Powe v. City of Chicago, [4] and Gay v. Wall. [5] The difficulties in later § 1983 cases claiming false imprisonment in this situation are (a) just how much of a delay is actionable, (b) whether a police officer or jailer satisfies any duty by informing prosecutors, and (c) determining who in the bureaucratic labyrinth of the criminal justice is liable.


[1] See, e.g., Tribulski v. County of Los Angeles, 83 Cal. App. 3d 828, 146 Cal. Rptr. 229, 230 (1978).

[2] Lambert v. McFarland, 612 F. Supp. 1252, 1270-1272 (N.D. Ga. 1985).

[3] Pennington v. Hobson, 719 F. Supp. 760, 777-779 (S.D. Ind. 1989).

[4] Powe v. City of Chicago, 664 F.2d 639 (7 th Cir. 1981).

[5] Gay v. Wall, 761 F.2d 195 (4 th Cir. 1985).