The term "adultery" refers to sexual acts between a married person and someone who is not that person's spouse. It may arise in a number of contexts. In criminal law, adultery was a criminal offence in many countries in the past, and is still a crime in some countries today. In family law, adultery may be a ground for divorce, with the legal definition of adultery being "physical contact with an alien and unlawful organ", while in some countries today, adultery is not in itself grounds for divorce. Extramarital sexual acts not fitting this definition are not "adultery" though they may constitute "unreasonable behavior", also a ground of divorce.