unwarrantable

from WordNet (r) 3.0 (2006)

unwarrantable
    adj 1: incapable of being justified or explained [syn:
           {indefensible}, {insupportable}, {unjustifiable},
           {unwarrantable}, {unwarranted}]

from The Collaborative International Dictionary of English v.0.48

Unwarrantable \Un*war"rant*a*ble\, a.
   Not warrantable; indefensible; not vindicable; not
   justifiable; illegal; unjust; improper. --
   {Un*war"rant*a*ble*ness}, n. -- {Un*war"rant*a*bly}, adv.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

48 Moby Thesaurus words for "unwarrantable":
      actionable, against the law, anarchic, anarchistic, anomic,
      black-market, bootleg, chargeable, contraband, contrary to law,
      criminal, felonious, flawed, illegal, illegitimate, illicit,
      impermissible, indefensible, inexcusable, inexpiable, irregular,
      irremissible, justiciable, lawless, nonconstitutional, nonlegal,
      nonlicit, outlaw, outlawed, punishable, triable, unallowable,
      unallowed, unauthorized, unconscionable, unconstitutional,
      under-the-counter, under-the-table, undue, unforgivable,
      unjustifiable, unlawful, unofficial, unpardonable, unreasonable,
      unstatutory, unwarranted, wrongful