body: I read that many laws are unenforced. What did the DA do to decide what to enforce and what not?
  
  
  For example. Say some states have laws against cohabitation. Say a DA choose to enforce the normally unenforced laws. What happens? The DA don't get reelected?
  
  
  Or look at this case
  
  
  <https://nypost.com/2017/11/28/mom-faces-jail-for-secretly-recording-daughters-bullies/>
  
  
  Some kids got bullied. DA don't press charge. Someone record the bullying, and she gets charged.
  
  
  Why?
  
  
  Also I've heard that many fraud are simply not enforced by laws. These are samples
  
  
  [Why are some obvious fraudster not in jail?](https://law.stackexchange.com/questions/31197/why-are-some-obvious-fraudster-not-in-jail)
  
  
  What factors do DA do when deciding when to press charge?
  
  
  Bribes? I don't think so. Not in US. But that's got to be something and it doesn't look like justice to me.
  
  
  The result varies from jurisdiction to jurisdiction. In, Indonesia, my guess is
  
  
  1. Bribe. Before Jokowi it's common for vengeful party to just pay DA to do his job. Defendant often have more incentive to pay DA to look the other way.
  2. Political opinion. Ahok is prosecuted because so many wants him down.
  3. Most fraud is not prosecuted. I don't know why.
  
  
  In US, what happens?
  
  
  Jurisdiction specific or "in general" answer is fine.
  
  
  Perhaps, a better more useful version of this question is
  
  
  How to motivate DA to prosecute or not prosecute a certain case?
  
  
  Jurisdiction vary. I know.
  
  
  Note: I've heard in US, DA is an elected office. So it seems that DA's motivation is to pick cases that gets him elected. That's the kind of thing I would like to know. What's the "politic" and "incentive" behind prosecuting a case.
  
  
  Saying that there is a large backlog of cases is not "clear" enough for me because it's a "collective" problem. The one that makes decisions is the DA. Why should he care about backlog? If prosecuting a case leads to world war that is not HIS problem. It's societies' problem. Because that gets him elected? Now it makes more sense.
  
  
  I need reasons that's why is it more profitable for a DA/cops to decide one case over another.
  
  
  Basically I am looking for incentives or cynical reasons those people have when prosecuting someone
  
  
  
title: What "incentives"/cynical reasons DA/Cops have when prosecuting someone?