According to Qatar's Constitution, Sharia law is the main source of Qatari legislation, although in practice, Qatar's legal system is a mixture of civil law and Sharia law. Sharia law is applied to family law, inheritance, and several criminal acts (including adultery, robbery and murder). In some cases, Sharia-based family courts treat a female's testimony as being worth half that of a man. Codified family law was introduced in 2006. Islamic polygyny is permitted.