We have a multilayered system in this country - which means that we have individual states and individual state laws and state courts; county/municipal laws and courts; and federal laws and federal courts.
Every state has different laws. The different cities in every state have different laws. If you're driving across the country, you might not want to pack your edible cannabis- which is legal in some states but can land you in deep trouble in others. Sometimes cities will have different laws from the state on guns or cannabis, and sometimes the state will tell the cities that, no, they can't have different laws. And don't forget that there's another layer - federal laws.
Federal law trumps state law except when it doesn't. Or when the Supreme Court says it doesn't.
Generally, violations of federal law go to federal court, violations of state laws go to state courts, violations of constitutional rights can be brought in either, but the federal courts are the last resort. Unless they don't want to be.
Most people understand that the laws are different. But court rules and court procedures are also widely different, and not just from state to state and from state to federal. Different federal district courts - within the same state or the same circuit - can have very different rules and procedures.
Whaddaya mean court rules and procedures?
Rules govern everything from how you file a case to how you try it - how much time you have to file to case, even how big the print has to be on your briefs. Violate those rules and it doesn't matter how good your case is -you can be an innocent person on death row - you can be the winner of the Nobel Peace prize - your case can and most probably will be dropped kicked out of court - and if you (or rather your lawyer) are out of time to fix it, you're done.
People with innocence claims have been executed because their lawyers missed filing deadlines.
Doesn't seem right - because it isn't right - but that's how this game is played.
There are too many cases and too many lawyers. Court clerks are delighted to find these technical mistakes that can cut down on the caseload. If clerks can find violations of a procedural rule, they're happy to drop kick that case, even at the cost of someone's life.
What does it mean for a lawyer?
As a lawyer, you have to know the rules in the court where you're practicing, and that also means you have to be admitted to practice in that particular court. Generally, you get admitted to a state, and you can practice anywhere in that state. You can try a case in family court or you can argue in the state supreme court. Whether you're competent to do either - whole other question - but as long you're admitted to the state, you're in.
Federal system - meh, not so fast. Every district court that you want to appear in - as in file a lawsuit, appear in court, whatever - you have to be admitted. Then you need to be admitted to the Court of Appeal to argue an appeal. And to argue in the Supreme Court, yup, have to admitted there too.
Keeping track of it all is a pain. It's why we lawyers feel justified charging the big bucks.
What does it mean for the writer?
If it's a crime story or a legal thriller that goes into the courtroom, the writer has to know not only what the laws are of the particular city/state where the story is set - but what court the case would be brought in. You don't have to go into the details - most people won't be interested in the technical aspects of lawyering. Just don't make a mistake that will have lawyers rolling in the aisles with laughter.
When in doubt, make friends with a lawyer in the right jurisdiction.