The Collaborative International Dictionary of English v.0.48:

lawbreaker \law"break`er\, law-breaker \law"-break`er\, n.
   One who disobeys the law; someone who violates the law; a
   criminal.

   Syn: violator, lawbreaker, law breaker, perpetrator.
        [1913 Webster + WordNet 1.5] -- Law"break`ing, n. & a.
        [1913 Webster]

WordNet (r) 3.0 (2006):

lawbreaker
    n 1: someone who violates the law [syn: violator,
         lawbreaker, law offender]

Moby Thesaurus II by Grady Ward, 1.0:

40 Moby Thesaurus words for "lawbreaker":
   Judas, bad person, betrayer, convict, criminal, crook, deceiver,
   delinquent, desperado, desperate criminal, double-dealer, evildoer,
   felon, fugitive, gallows bird, gangster, gaolbird, jailbird,
   malefactor, malevolent, malfeasant, malfeasor, misfeasor, mobster,
   offender, outlaw, public enemy, quisling, racketeer, scofflaw,
   sinner, swindler, thief, thug, traitor, transgressor, two-timer,
   villain, worker of ill, wrongdoer