Rei Interventus
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
Lat. Things intervening ; that is, things done by one of the parties to a contract, in the faith of its validity, and with the assent of the other party, and which have so affected his situation that the other will not be allowed to repudiate his obligation, although originally it was imperfect, and he might have renounced it.
1 Bell, Comm. 328, 329.