3 Answers

Depends on what the settlement check is for. Are you settling for a case he was your legal counsel for? Did he agree to the settlement in your name but you disagree with the settlement? Do not case the check if you disagree with the settlement. Is the settlement check to make up for the misconduct? You need to add more information before anyone can possibly answer this. 

What was the misconduct? Where did this occur? Does this rise to the level of malpractice? Did you have a retainer agreement with the attorney, and what, if anything are the settlement terms therein? Did the attorney settle without your consent? It seems as though the attorney might have taken too much for his/her share. If so, and it's substantial enough, it could rise to a level of criminality. Lastly, I would cash the check; it's not cashable forever. From the information you've provided, I infer that your beef, if any, is with the attorney.

You will save yourself a lot of time and money if you just report the attorney to the American Bar Association, or the local or state bar association where you live.  It's not YOUR job to sue him for "misconduct".