Wiktionary
house rule
n. A rule adopted by a particular establishment.
Wikipedia
House rule
House rules are rules applying only in a certain location or organization. Bars and pubs in which games take place frequently have house rules posted. For example, it is a house rule in United States Air Force officers' clubs that if an officer enters the club wearing headgear and is officially noticed (i.e., the bell near the bar is rung), the entering officer must buy a round of drinks for the bar.
In households, house rules are rules set by the head of the family, generally to be followed by children.
Usage examples of "house rule".
Apparently the police who had entered were women officers, so they were not breaking the house rule against men.