Sadly this is a reason why Police officers and firefighters must be NEVER be unionized.
Like the Military Army the police are a regimented(in a similar way) army of their own.
Indeed if one was so inclined one could seek to abolish the State police force by declaring it to be a professional standing army forbidden to the States in time of peace under the Constitution of 1787.
The point is this army now has a divide loyalty between to unions, the original union of the State among the whole of the people, and the New artificial union among themselves for the propose of their own financial well-being.
(never mind the warring against the same by the founders.)
The police ARE the standing army whose existence worried the Founders. The purpose of the standing army was to enforce the will of the rulers upon the populace.