You can write one law that all countries must enforce

The law can be anything.

It will remain in law for at least a year.

It will be enforced by the police, although individuals might choose to resign rather than continue depending on their personal views.

There won’t be corruption problems regarding enforcing this law. For example, if the police normally wouldn’t arrest someone for other crimes, they would for your law.

You can choose the punishment for anyone who breaks the law.