Personally, I think policemen or other government employees should NOT be allowed to unionize. I mean, just who is their employer?
Answer: ALL of us.
There are other careers out there if they find not be able to unionize as condition for government employment.
I remember back in the 1970s, while stationed in Europe, the Belgian armed forces were unionized. They went on strike because they did not want to play war games. In a real war, they would have been less than useless; giving aid and comfort to the enemy Soviets.
And we have no seat at the "collective bargaining" table.