“CEFCU's allegations constitute a threat to file a trademark infringement lawsuit against SDCCU should SDCCU continue to use its trademark for 'It's not big bank banking. It's better,'” it said in its complaint.

“SDCCU is not aware of any actual confusion between the SDCCU mark and the CEFCU mark,” it added.

San Diego County Credit Union, whose members are primarily in Southern California, has $8.4 billion in assets and about 385,000 members. Ci­­tizens Equity First Credit Union's members are primarily in Peoria, Illinois, and Northern California, according to the complaint. That credit union has $6.1 billion in assets and about 331,000 members.

Ci­­tizens Equity First Credit Union entered the California market after acquiring a credit union in Northern California in 2008, according to the complaint. It didn't use its slogan in California until June 2011, the complaint alleged.

San Diego County Credit Union also alleged that other credit unions' slogans were actually much more similar to CEFCU's slogan.

“It is common for credit unions like CEFCU and SDCCU to use taglines, logos, service marks, and/or trademarks, such as the CEFCU mark and the SDCCU mark, themed to distinguish credit unions and banks. For example, several third-party credit unions have used trademarks such as 'Not a bank – Better!' 'Better than a bank,' and 'It's not a bank,' in connection with their respective credit union services,” it said.

However, the complaint claims, CEFCU didn't seem to have a problem with the similarity of those slogans when it applied for its own trademark and allegedly had to have known it did not have exclusive rights to the phrase “Not a bank. Better.”

“Therefore, CEFCU added the word 'CEFCU' to the term 'Not a bank. Better,' in an attempt to differentiate its applied-for trademark from trademarks already used by other credit unions which were identical or similar to CEFCU's desired trademark of 'Not a bank. Better,'” San Diego County Credit Union claimed.

“The tagline 'Not a bank. Better,' merely describes that a credit union is not a bank, and therefore the tagline is not protectable as a trademark,” it said.

The conflict between the two credit unions apparently began in 2016 after a CEFCU employee saw a billboard in San Diego advertising SDCCU and using the phrase “It's not big bank banking. It's better.” About a year later, CEFCU asked the U.S. Patent and Trademark Office to cancel SDCCU's trademark.

SDDCU asked the court for damages and attorney fees, as well as declarations that its trademark doesn't infringe on CEFCU's trademarks and that CEFCU's trademarked slogan is invalid.