Jurisdiction is the power and right to apply and enforce the law.
As a simple example. You are in England and buy something online from France. You pay for it but it never arrives. No refund. You try to claim in court and issue a summons.
The seller could contest jurisdiction, claiming the English court has no authority in France where the contract was made.
Ok i think thats making sense now - thank you. My husband has received a court claim from his ex sister in law relating to money she leant him and his ex wife 20 years ago. My husband has paid it back before and shortly after his divorce but his ex sister in law is now trying to claim interest off him because the money she leant was from a re-mortgage on her house. There was never anything written down and my husband didn't know hwere she had had the money from but because her mortgage still has money outstanding on it she wants to claim against him. The papers give us the option of defending the claim or contesting jurisdiction
I would advise your husband to seek legal advice on this.
It could get very complicated. If your husband made the final payment many years ago, I would say that the ex-sister in law is 'out of time' and the claim is invalid. There are time limits on all civil claims.
Was there a formal contract in writing? Any demands for interest before now?