A tenuous “coexistence” agreement between Brooks and Brooks Brothers clothing company and retailer has fallen apart as the running shoe and apparel company last week filed a trademark infringement lawsuit against the similarly named brand.

The cause of the new dispute stems from Brooks Brothers’ 2018 move into selling athletic footwear, which Brooks contends will confuse consumers, damage its own marks and undermines that 1980 “coexistence” trademark agreement between the companies.

In a complaint filed in the federal court in Seattle, where it is based, Brooks challenged Brooks Brothers’ alleged effort to block it from registering its own trademark in the United States and other countries.

It also challenged Brooks Brothers’ Dec. 30, 2019, trademark application to use “Brooks,” without “Brothers,” on eight categories of items, including clothing and sporting goods, as well as on retail stores. Brooks is seeking damages, including for breach of contract, and to halt any infringements by Brooks Brothers.

“We will aggressively protect our intellectual property and defend the investment that’s created our valuable brand,” Brooks CEO Jim Weber said in a statement.