The Korean Intellectual Property Office announced that the amendment of the Unfair Competition Prevention and Trade Secret Protection Act ("UCPA"), including a provision to allow those who first used a trademark identical or similar to another person's well-known mark in Korea without improper purpose ("Good Faith Prior User") to continue using the trademark, entered into force on September 29, 2023.

Before this amendment to the UCPA, the provision prohibiting the act of using a mark similar or identical to another person's mark that is well-known in Korea to cause confusion as to the source of a product or business ("consumer confusion provision") did not have an exception for a Good Faith Prior User. Accordingly, a Good Faith Prior User could not use its mark after another person's mark became well-known in Korea. Unlike the consumer confusion provision, the UCPA's provision prohibiting trademark dilution allowed an exception for Good Faith Prior Users before the recent amendment. This was subject to some criticism as being unfair to Good Faith Prior Users.

In order to resolve such unfairness, this amendment to the UCPA allows an exception for Good Faith Prior Users by removing "acts of continuously using, without improper purpose, a mark similar or identical to another person's mark since before that mark became well-known in Korea" from the scope of acts considered to be unfair competition. At the same time, this amendment also includes a provision allowing the legitimate owner of a well-known mark to require Good Faith Prior Users to make and use labels as needed to prevent such confusion and/or deception, in order to remove the risk of consumer confusion and/or deception which may be caused due to the co-existence of the Good Faith Prior User's mark and another person's well-known mark in the same market.

It is expected that this amendment to the UCPA can protect Good Faith Prior Users from unexpected legal disputes. However, from the viewpoint of the owners of well-known marks, since there is a risk that they could bear unforeseen damages caused by the co-existence of identical or similar marks in the same market, it is strongly recommended for such owners to closely monitor their trademark use and seek appropriate measures against Good Faith Prior Users if necessary.