Your original question was a little unclear. I think you are asking about personal jurisdiction and subject-matter jurisdiction. In order for a court to enter a judgement in a case--indeed, in order for a court to hear a case--that court must have appropriate personal jurisdiction or subject-matter jurisdiction. If the court is found to not hold the appropriate jurisdiction over a type of claim, then any judgement rendered may be found void. Examples of subject-matter jurisdiction are medical malpractice and family law. Examples of personal jurisdiction are tort and contract law.
I am going to disagree with the above post. For a court to enter a valid judgment, it must have both subject matter jurisdiction and personal jurisdiction. Subject matter jurisdiction is exactly what it sounds like: jurisdiction of the subject of the case. A federal court can't hear divorces. State courts will not take a bankruptcy petition. Personal jurisdiction is the ability to enter a judgment against a particular person. Personal jurisdiction applies to persons. A state cannot grant a divorce to one spouse if it does not have personal jurisdiction over the other spouse. With out-of-state parties personal jurisdiction can be a problem.