> Unless they are willing to go to war they can't do shit to people outside their jurisdiction by definition, if they had power over that place it would be part of their jurisdiction.
True, but effective jurisdiction can be much bigger than you might think, especially in civil matters.
Suppose X is in country Cx, and Y is in country Cy.
X travels to Cy, and while there sells some item to Y, and then goes home to Cx. X ends up getting sued in Cy over this transaction, and loses, and the court in Cy awards a civil judgment to Y.
In many countries Cx, Y can bring that judgment he got in Cy to a court in Cx, and that court will decide if the court in Cy had jurisdiction. In this example, there is a good chance they will say that it did. They will say it had personal jurisdiction over X because X was in Cy for the transaction. They also will look at how the courts work in Cy to ensure that they meet similar standards for fairness as the courts in Cx. If they do the court in Cx might issue a civil judgment good in Cx to enforce Cy's judgment.
(If X did not defend himself in the Cy court, the Cx court might hold its own trial to allow a defense, applying Cx procedure but using Cy substantive law).
In the above example, X was actually in Cy when the transaction happened that led to a civil action in Cy. I think most countries would agree that gives Cy personal jurisdiction.
If X is not actually in Cy, but conducts business with people in Cy by mail, phone, or internet it would be less clear. If you were specifically targeting Cy people with ads and shipping goods to there, there is probably a good chance Cx would decide that is sufficient. If you were not shipping physical goods and not doing anything specifically to target Cy, then Cy might not have personal jurisdiction.
Anyway, the bottom line is that if you are actually doing business with people in another jurisdiction, even if you have no physical presence in that jurisdiction and no assets in that jurisdiction, it is not wise to just assume that a civil judgment against you in that jurisdiction will not be enforceable. You really need to look at exactly how your jurisdiction deals with foreign judgments.