In a will, this is a sentence or secret character inserted by the testator, of which he reserves the knowledge to himself, with a condition that no will he may make thereafter should be valid, unless this clause be inserted word for word. This is done as a precaution to guard against later wills being extorted by violence, or otherwise improperly obtained. By the law of England such a clause would be void, as tending to make the will irrevocable. Wharton.
Derogatur legi, cum pars detrahitur; abrogatur legi cum prorsus tollitur. To derogate from a law is to take away part of it; to abrogate a law is to abolish it entirely. Dig. 50, 17, 102.