Massachusetts General Laws Part III. Courts, Judicial Officers and Proceedings in Civil Cases (Ch. 211-262) Ch. 246, § 26

A trustee may retain or deduct from the goods, effects or credits in his hands all liquidated demands or judgments against the defendant of which, had he not been summoned as trustee, he might have availed himself upon a trial or by the set-off of judgments or executions between himself and the defendant, and he shall be liable for the balance only after all mutual demands, excluding therefrom any claim on either side for unliquidated damages for wrongs or injuries, between himself and the defendant have been adjusted.