The Collaborative International Dictionary of English v.0.48:

Litigious \Li*ti"gious\, a. [L. litigiosus, fr. litigium
   dispute, quarrel, fr. litigare: cf. F. litigieux. See
   Litigation.]
   1. Inclined to initiate lawsuits; given to the practice of
      contending in law; fond of litigation. " A pettifogging
      attorney or a litigious client." --Macaulay.
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            Soldiers find wars, and lawyers find out still
            Litigious men, who quarrels move.     --Donne.
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   2. Hence: Quarrelsome; contentious; argumentative.
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   3. Subject to contention; disputable; controvertible;
      debatable; doubtful; precarious. --Shak.
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            No fences, parted fields, nor marks, nor bounds,
            Distinguished acres of litigious grounds. --Dryden.
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   4. Of or pertaining to legal disputes.
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            Nor brothers cite to the litigious bar. --Young.
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WordNet (r) 3.0 (2006):

litigious
    adj 1: of or relating to litigation
    2: inclined or showing an inclination to dispute or disagree,
       even to engage in law suits; "a style described as abrasive
       and contentious"; "a disputatious lawyer"; "a litigious and
       acrimonious spirit" [syn: contentious, combative,
       disputatious, disputative, litigious]