A more thorough explanation:

The comity of nations doctrine is a principle that allows recognition of foreign proceedings as long as they are deemed fair, orderly, and not harmful to another country's interests. It is not a constitutional obligation for U.S. courts to recognize or enforce foreign judgments, but it is still used for public policy reasons.

Under the comity of nations principle, a reviewing court does not reopen cases that have already been heard in other courts. Instead, it examines the foreign judicial system and considers factors such as fairness, impartiality, personal jurisdiction, subject matter jurisdiction, and the presence of fraud. If the foreign court's judgments meet these criteria, the reviewing court may choose to respect and enforce them.

For example, if a U.S. court is asked to enforce a judgment from a Canadian court, it will consider whether the Canadian court's proceedings were fair and orderly. If the U.S. court determines that the Canadian court's proceedings meet the criteria, it may choose to enforce the judgment.

The Restatement factors are also considered when deciding whether to exercise jurisdiction in deference to the laws and interests of another foreign country. These factors include the link of the activity to the territory of the regulating state, connections between the regulating state and the person responsible for the activity, the character of the activity to be regulated, and the importance of regulation to the regulating state.

Overall, the comity of nations principle is used to promote international cooperation and respect for the laws and interests of other countries.