Est aliquid quod non oportet, etiam si licet; quicquid vere non licet certe non oportet

Dictionary: 
Ballentine's Law Dictionary

Something may not be proper although it is lawful, but certainly anything which is not lawful is not proper.

Author: 
James A. Ballentine
Publisher: 
The Bobbs-Merrill Company
Year Published: 
1916
Genre: 
Law Dictionary