The Treason Act 1586 or the Errors in Attainders Act 1586^[1] (29 Eliz. 1. c. 2) was an Act of the Parliament of England. Its long title was "An act concerning errors in records of attainders of high treason." It stated that where a person had been executed for high treason, their conviction was not to be posthumously overturned or "reversed" at the suit of their heirs. This was because (according to the Act's preamble) "through corruption or negligent keeping, the records of attainders of treason happen many times to be impaired, blemished or otherwise to be defective." The Act was intended to prevent people from taking advantage of this.

The Act did not apply to any writ of error which had already been brought, or affect any record which had already been reversed.