The power of arrest is a mandate given to certain members of a society by the central authority that allows them to remove a criminal or suspected criminal's liberty. The power of arrest can also be used to protect a person, or persons from harm or to protect damage to property.
Arrest usually leads to police custody. In many countries, the power of arrest has now been extended to not only the Police, but to other law enforcement agencies such as Immigration, Customs & Excise and authorised Bailiffs, etc.
However, in many countries, a person also has powers of arrest under citizen's arrest or any person arrest powers.