Well we can point to one example where he enforced the military justice system he was charged with setting up and did not intercede when it ordered a member of his own guards to be hung.

Early in the war as the Continental Army was occupying New York City, a member of the Commander-in-Chief's Guard, one Thomas Hickey, was arrested by civil authorities for counterfeiting and while in prison told another inmate of a group of soldiers in the Guard who were involved in a conspiracy and in the pay of Loyalists to either defect or cause all manor of mayhem to the Continentals or even capture Washington himself, with the Mayor of NYC even being connected possibly.

Tried by a Court-Martial he was hung in front of a large square in June 1776. Washington as Commander-in-Chief had the power to overturn, offer a pardon, or diminish the punishment ordered by the Court, that he did not obviously shows that if nothing else he was willing that the discipline process he was attempting to build should operate as normal.

In general the CIC was often a stickler for discipline, mostly because for much of the war the men he commanded were so very raw that without a firm hand it all could easily have fallen apart. Especially in the lean times and later years of the war where though the remaining Continentals were well drilled they were nursing deep grievances at the support, pay, and supplies received. In another instance several hundred soldiers of the New Jersey Line began to march on Trenton to demand redress(in emulation of a recently mostly bloodless and peaceful act by the Pennsylvania troops). This time though in what has been called the Pompton Mutiny, Washington dispatched troops to demand the unconditional submission of the troops, which in the end resulted in the execution by firing squad of a handful of ringleaders.

And while not exactly the category you asked about we have Washington appointing and abiding by a Military Tribunal's decision that Major John Andre was acting as a spy and should be hanged. The Tribunal was headed by Nathanial Greene, Washington's 2nd in Command, included as well von Steuben, and even Lafayette, virtually every senior officer in the main army was involved in the decision save Washington himself. That provided him a key level of separation to possibly overrule them, but he could not possibly have been of completely separate opinion or not actively known the minds and likely decision of the board. Andre was a British Officer and had been instrumental in the defection of Benedict Arnold, being then captured in civilian clothes behind American lines.