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