One in, one out policy

During the COVID-19 pandemic, stores controlled entry to limit numbers of shoppers.

A one in, one out policy is a method used to control the number of people in one place or building at any one time. Where a place or building has reached its maximum capacity, further entry is only allowed upon a person leaving. It is especially used in nightclubs and bars, and most military establishments.

The term is also used in reference to immigration. For example, as of mid-2025, the United Kingdom and France are discussing a plan under which, for every migrant sent back from Britain to France, France would send an asylum seeker to the UK — possibly one with a family connection to Britain.