legal separation

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A court decree recognizing that a married couple is living apart and regulating the couple's mutual rights and liabilities. Also called judicial separation.

WordNet 3.0

1. n. a judicial decree regulating the rights and responsibilities of a married couple living apart
2. n. (law) the cessation of cohabitation of man and wife (either by mutual agreement or under a court order)