A more thorough explanation:

The Berne Safeguard Clause is a provision in the Universal Copyright Convention that prevents protection in Berne Union countries for the works of any country that withdraws from the Berne Union after January 1, 1951. This means that if a country decides to leave the Berne Union, their works will not be protected in other countries that are part of the Berne Union.

The purpose of this clause is to discourage countries from leaving the Berne Union in favor of more relaxed copyright-protection standards of other conventions. This helps to maintain a consistent level of copyright protection across different countries.

For example, if a country decides to leave the Berne Union and join a different convention with weaker copyright protection standards, their works will not be protected in Berne Union countries. This means that their works can be freely used and distributed in those countries without any legal consequences.

The Berne Safeguard Clause was amended in 1971 to give developing countries the right to opt out of its mandate. This means that developing countries can choose not to follow this provision if they feel that it would be detrimental to their interests.