Malise took an active part in opposing the invaders, commanding the third division of the Scots army at the Battle of Halidon Hill, and was referred to as a "notorious rebel" by Edward III.
Malise made strenuous efforts to recover Strathearn, but without success, and he went to dwell on his estates in Caithness.
During King David's absence in France, he was arraigned before the High Steward and accused of felony and treason, in that he had supposedly resigned the earldom of his own free will by reason of a contract between him and the Earl of Surrey.
The jury acquitted him, but the earldom remained in David's hands, who in 1344 bestowed it on Malise's nephew Maurice de Moravia.
He pleaded that he had already been found innocent; this was partly acknowledged by Parliament, though they judged that the earldom should continue to be held by the King.