A more thorough explanation:

In perpetuum rei testimonium (in pər-pet-yoo-əm ree-ee tes-ti-moh-nee-əm), is a Latin phrase used in law. It means "in perpetual testimony of a matter." This phrase refers to a statute that confirms existing common law.

For example, if a law has been in place for a long time, but people are starting to forget about it or argue about what it means, the government might pass a new law that says "in perpetuum rei testimonium" to confirm that the old law is still valid and should be followed.

Another example is when a court makes a ruling that sets a new legal precedent. If the ruling is important and should be followed in the future, the court might use the phrase "in perpetuum rei testimonium" to make it clear that this ruling should be considered part of the law from now on.

The examples illustrate how the phrase "in perpetuum rei testimonium" is used to confirm or establish the validity of existing laws or legal precedents. It is a way of making sure that everyone knows what the law is and that it will continue to be followed in the future.