Boone v Eyre (1777) 1 H Bl 273 is an English contract law case, concerning the concept of a "condition precedent".
Boone v Eyre Wikipedia
The plaintiff sued the defendant for not paying a £160 annuity (for life) for a plantation in the West Indies that came with a group of slaves, after an initial payment of £500. The defendant contended that when the plaintiff made the deed, the plaintiff did not lawfully possess the slaves, and therefore had no good title. Therefore, the defendant was arguing he had the right to terminate the agreement and cease performance.
Lord Mansfield said the following.