Godan verb with 'ru' ending, Intransitive verb
to follow (a rule, precedent, style, etc.); to conform to; to be in accordance with
利益追求に必死のブローカーは、必ずしもルールブックにのっとっているとは限らないのです。Brokers struggling to make a profit don't always play by the book.
Also written 法る【のっとる】、乗っ取る【のっとる】