Casus omissus

Casus \Ca"sus\, n. [L.]
   An event; an occurrence; an occasion; a combination of
   circumstances; a case; an act of God. See the Note under
   {Accident}.
   [1913 Webster]

   {Casus belli}, an event or combination of events which is a
      cause war, or may be alleged as a justification of war.

   {Casus fortuitus}, an accident against which due prudence
      could not have provided. See {Act of God}, under {Act}.

   {Casus omissus}, a case not provided for by the statute.
      [1913 Webster]
    

CASUS OMISSUS. An omitted case. 
     2. When a statute or an instrument of writing undertakes to foresee and 
to provide for certain contingencies, and through mistake, or some other 
cause, a case remains to be provided for, it is said to be a casus 
omissus.For example, when a statute provides for the descent of intestates 
estates, and omits a case, the estate descends as it did before the statute, 
whenever that, case occurs, although it appear to be within the general 
scope and intent of the statute. 2 Binn. R. 279. 
     3. When there has been a casus omissus in a statute, the subject is 
ruled by the common law: casus omissuset oblivioni datus dispositioni juris 
communis relinquitur. 5 Co. 38. Vide Dig. 38, 1, 44 and 55 Id. 38, 2, 10; 
Code, 6, 52, 21 and 30.