The Collaborative International Dictionary of English v.0.48:

Arrogate \Ar"ro*gate\, v. t. [imp. & p. p. Arrogated; p. pr. &
   vb. n. Arrogating.] [L. arrogatus, p. p. of adrogare,
   arrogare, to ask, appropriate to one's self; ad + rogare to
   ask. See Rogation.]
   To assume, or claim as one's own, unduly, proudly, or
   presumptuously; to make undue claims to, from vanity or
   baseless pretensions to right or merit; as, the pope
   arrogated dominion over kings.
   [1913 Webster]

         He arrogated to himself the right of deciding
         dogmatically what was orthodox doctrine. --Macaulay.
   [1913 Webster]