What is the test for "comity" in international law?

Comity is the principle in accordance with which the courts of one jurisdiction will give effect to the laws and judicial decisions of another, not as a matter of obligation, but out of deference and respect. The principle is well described by La Forest J. in Morguard v. De Savoye, supra, at 1096: Comity in the legal sense is neither a matter of absolute obligation, on the one hand, nor of mere courtesy and good will, upon the other. But it is the recognition which one nation allows within its territory to the legislative, executive, or judicial acts of another nation, having due regard both to international duty and convenience, and to the rights of its own citizens or of other persons who are under the protection of its laws ... .