In general, legal documents sent back to the country from any country usually need to be notarized or authenticated, but there are exceptions as follows:
Contracting States of China to the Convention Abolishing the Requirement of Legalisation for Foreign Public Documents:
Starting from November 7, 2023, China officially implements the "Convention on the Abolition of the Requirement of Legalization for Foreign Public Documents." Countries such as Japan, South Korea, Singapore, Finland, France, Germany, Spain, Sweden, Switzerland, Ukraine, the United Kingdom, Russia, the United States, Australia, New Zealand, and others are contracting parties to this Convention. Legal documents sent from these countries only need to obtain an additional certificate from the respective country, without requiring consular legalization from the local embassy or consulate of that country and China.
Countries with "exemption from certification" clauses in bilateral judicial assistance treaties: If a bilateral judicial assistance treaty signed between China and certain countries explicitly stipulates the exemption from certification requirements for specific types of legal documents, then legal documents sent back from these countries can be enforced according to the treaty without the need for additional notarization or certification, but this situation is relatively rare.
However, even in the above situations, for some special legal documents or in specific judicial practices, further evidence or review may still be required based on specific circumstances.