I think the old, sound, and honest maxim that "you shall not do evil that good may come," is applicable in law as well as in morals.
Reg. v. Hicklin and another (1868), 11 Cox, C. C. 27; S. C. 3 L. R. Q. B. 372; reported in Dictionary of Legal Quotations (1904) by James William Norton-Kyshe, p. 92.