What are the factors that determine whether or not a case may be charged in federal or state court?

Answer 1

It depends on whether it is a civil or criminal matter.

For civil cases -- there are some lawsuits that are exclusively under federal jurisdiction (bankruptcy, copyright, maritime law, etc.) -- and some that are based on state law claims (most torts, breach of contract) -- and some that can be either. The first issue is what law allows you to sue.

But there is still the issue that federal courts can only be used for civil lawsuits if you are suing under a federal law -- or if the other party is a resident of a different state and the amount is high (over $75K) -- that last is called diversity jurisdiction. Other than that, you have to start in state courts.

For criminal matters -- it depends who brings the charges, based on what laws were broken -- federal agencies bring prosecution in federal courts for violation of federal laws -- state agencies in state courts for violation of state laws.

Answer 2

For crimes, the first criteria is whether or not any federal laws have been broken. Not every criminal offense is federal.

If it is both a federal and state matter, the prosecutors will decide which one will take priority, based on likelihood of conviction (rules differ), penalties, and sometimes egos come into play.

Federal usually gets it if they want it.