If he doesn’t pay me, I’ll take him to the courts.
If he doesn’t pay me, I’ll take him to court.
He will have to appear in the court next Monday.
He will have to appear in court next Monday.
When someone is involved in a legal case, use the singular form court without an article: ‘go to court’, ‘take somebody to court’, ‘appear in court’ and ‘be in court’.
Use the court when referring to a particular court building or to the people who make a legal decision: ‘Reporters were waiting outside the court.’ ‘The court found him guilty.’