Five hundred years ago, when the world’s economy first began to become global, there existed a 15,000 kilometre unbroken chain of law courts in many seaports situated on the the north-eastern coast of China down through south-east Asia, westwards through India and the Mediterranean, and north-westwards along the coastline of western Europe finally ending when it reached the Baltic.
These were the mercenary courts — the ones that applied justice between merchants — and were little noticed by the public or the powers-that-be in the uniquely different cultures — each with its own statutory laws — along the route. They only chose to prosecute merchants and adjudicate between them on the evidence of bad debts or broken transactions, etc.
The judges — fellow merchants — had no powers of punishment such as goal, nor did they want them because they have a maintenance cost. Any merchant found guilty would simply be ‘sent to Coventry’ — ignored — from then onwards. They would be unable to operate as merchants from then onwards. Ports and courts along the same stretch of coastline would hear the verdict first, but more distant ones in different cultures would also get to hear sooner or later by the usual grapevine.
The mercantile courts had no powers of arrest. A plaintiff merchant would have to wait until he managed to catch an offending merchant in port and then apply to the local court for punishment or restitution in some form. Thus a Swedish merchant could process a claim on a Chinese merchant — and show the evidence — in an Egyptian court. If the offending merchant were found guilty then the news would spread along the chain in the same way as if the court had been held in either China or Sweden (probably in half the time, actually!).
The reason why the location of the court doesn’t matter much is that verdicts were arrived at on the basis of evidence and common sense, not the statutory law which governments use to control the general public. For ‘common sense’ read common law or case law or equity law. There are only two ports these days where common law is still practised. These are London and New York. There’s evidence that the use of common law is now growing again to its former importance.