Legal separation (sometimes "judicial separation", "separate maintenance", "divorce a mensa et thoro", or "divorce from bed-and-board") is a legal process by which a married couple may formalize a de facto separation while remaining legally married. A legal separation is granted in the form of a court order.

Furthermore, in cases where children are involved, a court order of legal separation often makes temporary arrangements for the care, custody, and financial support of the children ("for the time being"). Thus, part of the court order determines child custody. Some couples obtain a legal separation as an alternative to a divorce, based on moral or religious objections to divorce.

Legal separation does not automatically lead to divorce. The couple might reconcile, in which case they do not have to do anything in order to continue their marriage. If the two do not reconcile, and they wish to proceed with a divorce, they must file for divorce explicitly.

A mensa et thoro is a Latin phrase which means "from table and bed", often translated as "from bed and board", in which "board" is a word for "table". Separation a mensa et thoro is essentially a separation that is sanctioned by a court order, meaning that the spouses may legally live apart, but they are still legally married. The legitimacy of any future child born to the couple remains intact, and the spouses may not legally remarry. This type of separation allows the couple to live apart without concerns about being taken to court for "desertion". (In some jurisdictions, provable "desertion" is legal grounds for a divorce.)