English to Croatian Law/Patents Law (general)

I've got a Certificate of Authority (Punomoć), with an abbreviation of a title, I guess.
A company authorizes a person to execute bid proposals, agreements etc. and on the end there is a signature of the General Counsel of the company. I figured it must be Law related as this is a General Counsel and found Adv. stands for Adversary in Law... Still, no idea how to translate it as a title, after a person's name. Protivnik, suparnik - makes no sense??

John Miller, Adv.