Legal Definitions - primer seisin

Definition: Primer seisin is the right of the Crown to receive one year's profits of an inherited estate (or half a year's profits if the estate was in reversion) from the heir of a tenant who died in possession of a knight's fee.

Example: If John inherited a piece of land from his father who died while in possession of a knight's fee, John would have to pay the Crown one year's profits of the land as primer seisin.

This example illustrates how primer seisin was a way for the Crown to collect revenue from inherited estates.