What are the policy guidelines set by the US State Department to certify or legalize certain notarial documents?

The certificate(apostille) does not grant any immunity, and it should not be used to suggest that it does If the document is intended for use in the United States or in a country that is not part of the Convention of The Hague Single Legalization.

It is only for documents to be used in countries that are part of the Convention.

See the website of the Hague Conference on Private International Law for a current list of countries in which the Convention is in force.