You might want to rethink that.
If an international court had been in existence then, numerous British government officials would have been indicted and tried, and undoubtedly convicted, of corruption in government (pocket and rotten boroughs, of which Pitt the Younger was a flagrant violator, the suspension of habeas corpus twice during the period, gradual and more severe repressive government measures against the civilian population, a very severe penal code, as well as religious intolerance and persecution as well as what might amount to genocide against the Irish, to name a few).
So, your crusade against Napoleon tends to look somewhat insignificant when matched against the abuses against their own population by His Majesty's Government.