mala prohibita

from The Collaborative International Dictionary of English v.0.48
Mala \Ma"la\, n. pl.; pl. of {Malum}. [L.]
   Evils; wrongs; offenses against right and law.
   [1913 Webster]

   {Mala in se} [L.] (Law), offenses which are such from their
      own nature, at common law, irrespective of statute.

   {Mala prohibita} [L.] (Law), offenses prohibited by statute,
      as distinguished from {mala in se}, which are offenses at
      common law.
      [1913 Webster]
    
from Bouvier's Law Dictionary, Revised 6th Ed (1856)
MALA PROHIBITA. Those things which are prohibited by law, and therefore 
unlawful. 
     2. A distinction was formerly made in respect of contracts, between 
mala prohibita and mala in se; but that distinction has been exploded, and, 
it is now established that when the provisions of an act of the legislature 
have for their object the protection of the public, it makes no difference 
with respect to contracts, whether the thing be prohibited absolutely or 
under a penalty. 5 B. & A 5, 340; 10 B. & C. 98; 3 Stark. 61; 13 Pick. 518; 
2 Bing. N. C. 636, 646. 
    

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