In practice police can "turn a blind eye" - there are so many silly laws that if the police went around enforcing them all without interpretation they'd never be able to get anything done (kind of like a depth-first traversal). Generally speaking police have the freedom to pass over many misdemeanours unless they have been instructed not to.

Well it isn't as black and white as you're painting it. It is correct that sometimes law enforcement are obliged to enforce laws they as a group or as individuals do not agree with. On the other hand law enforcement are not obliged to enforce all laws all the time at any cost.

The legal principle of proportionality states that law enforcement always have to consider whether their actions are reasonable in comparison to the violation of laws.

https://en.wikipedia.org/wiki/Proportionality_(law)

There is also a general concept related to proportionality that basically states that law enforcement actions must be strictly necessary or required in the given situation. Especially when the means of enforcement includes physical violence.

http://www.ohchr.org/EN/ProfessionalInterest/Pages/UseOfForc...