The Collaborative International Dictionary of English v.0.48:

Triable \Tri"a*ble\, a. [From Try.]
   1. Fit or possible to be tried; liable to be subjected to
      trial or test. "Experiments triable." --Boyle.
      [1913 Webster]

   2. (Law) Liable to undergo a judicial examination; properly
      coming under the cognizance of a court; as, a cause may be
      triable before one court which is not triable in another.
      [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "triable":
   actionable, against the law, anarchic, anarchistic, anomic,
   black-market, bootleg, chargeable, contraband, contrary to law,
   criminal, felonious, flawed, illegal, illegitimate, illicit,
   impermissible, irregular, justiciable, lawless, nonconstitutional,
   nonlegal, nonlicit, outlaw, outlawed, punishable, unallowed,
   unauthorized, unconstitutional, under-the-counter, under-the-table,
   unlawful, unofficial, unstatutory, unwarrantable, unwarranted,
   wrongful