This idiom or expression has to do with:

Getting out of a bad legal situation without being punished.

A. Didn’t they arrest him for stealing from his mother?!
B. Yeah, but somehow he beat the rap and avoided going to jail!!

Also see:
Get away with something.

This idiom or expression has to do with traffic accidents.

Hit-and-run is when you hit someone (have an accident) but you don’t stop to help or identify yourself. Even if the accident is a minor one, it’s still considered “hit-and-run” with a more serious punishment.

Also see:
Hit and run.

This idiom or expression means:

Easy.
Quick.
Something that won’t require a lot of effort to finish.

A. You promised to go out tonight!
B. This won’t take long. It’s an open and shut case. We can still go.

This idiom or expression means:

Answering questions truthfully.
Going to the witness stand (in a court of law) and answering questions under oath.

As a witness you’ll have to take the stand and answer questions truthfully! Are you ready to do that?

This idiom or expression means:

The task of proving something.

The burden of proof for his innocence is on me!! I’m the one who’s supposed to prove that he’s innocent!

This idiom or expression means:

After something has happened.

Your honor, the evidence was planted at the scene after the fact.
You’ve already signed the contract. You can’t change it after the fact!

This idiom or expression like phrase means:

Something bad happening to a person as a result of something bad that the same person has done, and in the same (or similar) way or manner or setting.

Example:
An attorney defends a murderer and helps him escape conviction using a little known loophole. The same murderer (or maybe even another person) later murders the same attorney (or maybe a member of his family) and is found not guilty by using the same loophole. This is what’s called “Poetic justice”.

This idiom or expression like phrase means:

Keeping quiet.
Refusing to testify.

A. So, tell me about your date. What did you guys do last night?
B. Oh, I don’t know! I guess I’m gonna plead the Fifth. I’m not saying anything!!

Running away after being bailed out of jail and before the trial.

Helping.

I’m tired of bailing you out of your problems.

Also, similar usage:
Helping someone out of jail by paying the bail money.