Without a jurisdiction clause you litigate where your counterparty is domiciled. With one in the form Article 25 recognises, you do not — and the judgment that follows is enforceable across the Union without any declaration of enforceability, on four narrow grounds of refusal.
Where you end up by default, and why it is rarely where you want to be
One EU regulation decides which court hears a cross-border dispute inside the EU, and what happens to the judgment afterwards. Its starting point is simple: someone based in an EU country is sued in the courts of that country, whatever their nationality. They can be sued somewhere else only on the grounds the regulation itself allows.
So if your contract says nothing about it, you litigate where your counterparty sits. That is the single most common thing a commercial negotiation gets wrong — not by choosing badly, but by never discussing it.
The alternatives you do get
There are optional grounds as well, and two of them matter in ordinary trade:
Contracts. You can sue in the courts for the place where the obligation was to be performed. Unless you agreed otherwise, that means where the goods were or should have been delivered, or where the services were or should have been provided.
Damage. You can sue in the courts for the place where the harm happened, or may happen.
These are extra options, not replacements for the defendant's home court. They also depend on facts — where delivery happened, where performance happened — which is why they usually produce an argument before they produce a hearing.
A jurisdiction clause, and what makes one work
You can agree which country's courts will decide, whatever country either of you is based in. That choice is exclusive unless you agree otherwise, and it stands unless the agreement is invalid under the law of the country you chose.
The form is the part that fails in practice. The agreement has to be in writing or evidenced in writing; or in a form matching how the two of you have done business before; or, in international trade, in a form that follows a usage you knew or should have known about. An exchange of emails can meet the first. A term printed on the back of an invoice sent after the deal usually does not.
One practical point about exclusivity: naming one country's courts also keeps the dispute away from all the others. That is often worth more than the convenience of the court you picked.
What happens to the judgment
This is where the regulation earns its place in a contract negotiation. A judgment given in one EU country is recognised in all the others with no special procedure, and if it can be enforced at home it can be enforced in the others without any declaration of enforceability. There is no separate court process to go through first.
What you produce instead is modest: a copy of the judgment that meets the conditions for proving it is genuine, and a certificate from the court that gave it, confirming it is enforceable and setting out an extract, with details of recoverable costs and interest where relevant. Enforcement itself then runs under the local law of the country where you are enforcing, on the same terms as a judgment from its own courts — and an enforceable judgment automatically carries the power to take whatever protective measures that country provides.
The grounds for refusing, which are few
A court can refuse to recognise a judgment on a short list of grounds: recognition would be manifestly contrary to public policy; it was given in the defendant's absence and the defendant was not served in time, or in a way that let them arrange a defence, unless they could have challenged it and did not; it cannot be reconciled with a judgment between the same parties in the country where you are enforcing; or with an earlier judgment from somewhere else that qualifies for recognition.
What is not on that list: that the first court got the law wrong. The system trades a second look for speed.
What to do about it
Decide jurisdiction when you sign, not when you sue — and put it in one of the forms above.
Keep proof of service. Defective service is the refusal ground most often available to a defendant who ignored the proceedings.
Ask early where the assets are. The judgment travels across the EU; the enforcement procedure is still the local one.