Williams v. Taylor, 529 U.S. 420 (2000), was a United States Supreme Court case concerning the interpretation of a provision of the Antiterrorism and Effective Death Penalty Act of 1996 (AEDPA).

In a unanimous opinion written by Justice Anthony Kennedy, the Supreme Court held that the provision at issue[1] only bars evidentiary hearings by state prisoners in federal habeas proceedings if "there is lack of diligence, or some greater fault, attributable to the prisoner or his counsel".

[2] This case concerned a convicted murderer, Michael Wayne Williams, who was incarcerated at Sussex State Prison in Waverly, Virginia.

Confusingly, it was decided on the same day as another case called Williams v. Taylor, which concerned Terry Williams, a different convicted murderer incarcerated at the same prison; both cases named the prison's warden at the time, John B. Taylor, as the respondent.

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