I agree with the others. If this is a personal legal matter, you probably don't have any legal recourse if you get fired.
For example, is your court date on a family law matter? That's personal.
Another example, you are suing someone civilly for damages (reason immaterial) or someone is suing you civilly because that person believes you damaged them. Again, that's personal.
Finally, if your court date is because of some criminal charges that the state lodged against you or a sentencing hearing for example, again that likely is personal.
On the other hand, if you were subpeoned as a witness, some states will protect your job although even here, some of these laws and rules may not apply to small employers. (It sounds like you do work for a rather small employer.)
If your court appearance was mandatory and you do get fired, you probably will qualify for Unemployment Compensation (UI). It certainly costs you nothing to file for same, if you do lose your job over this matter.