An act of holding or retaining possession of property (typically real property) without a legal right to do so. The word “Detain” means to prevent from proceeding or to hold back someone or something – such as when police “detain” someone. The term “unlawful detainer” is most commonly used to refer to the act of a tenant who is in possession of real property (such as living in an apartment or house) who refuses to leave after the expiration or termination of the lease term.
When a landlord wants to recover the property after the tenant continues to stay on the property after termination of the lease, the landlord brings an eviction proceeding that is commonly called an action for “unlawful detainer.” Each state has its own laws that govern unlawful detainer proceedings and consist of specific procedural requirements. The landlord must serve notice upon the tenant according to state law in order to file and conduct a proceeding for unlawful detainer.