“Turning state’s evidence” means a person involved in a crime agrees to cooperate with prosecutors and testify against other people involved, usually in exchange for a lighter sentence or other leniency. In plain English, it’s similar to flipping on accomplices.

How it’s used

  • A defendant or witness gives information for the prosecution.
  • The testimony is aimed at co-defendants, accomplices, or conspirators.
  • The person often gets a plea deal, reduced charges, or immunity in return.

Example

  • “After being arrested, he turned state’s evidence and testified against the gang leader.”

Plain-language version

If someone “turns state’s evidence,” they switch sides and help the government build its case against others.

TL;DR: it means cooperating with prosecutors against other criminals, usually for leniency.