If the ability to cover up criminal acts is a consequence of police unions, there’s no doubt in my mind that they should be abolished.
Unions make a lot of sense, unless they can negotiate impunity on behalf of their members.
EDIT: Interesting article on this subject: https://www.nationalaffairs.com/publications/detail/the-trou...
Quote from the article:
When it comes to advancing their interests, public-sector unions have significant advantages over traditional unions. For one thing, using the political process, they can exert far greater influence over their members' employers — that is, government — than private-sector unions can. Through their extensive political activity, these government-workers' unions help elect the very politicians who will act as "management" in their contract negotiations — in effect handpicking those who will sit across the bargaining table from them, in a way that workers in a private corporation (like, say, American Airlines or the Washington Post Company) cannot. Such power led Victor Gotbaum, the leader of District Council 37 of the AFSCME in New York City, to brag in 1975: "We have the ability, in a sense, to elect our own boss."
2. There is no guarantee that the candidate you helped elect in your district will be the person responsible for negotiations. Other politicians are supposed to be a counterbalance to this, if they are doing their jobs, and actually give two figs about conflicts of interest.
This is largely a theoretical concern.
The concern I cited - that management is part of the union is not theoretical. It is one we've seen played out again and again.