As expected, the City of San Francisco has filed a trademark infringement suit against the Port of Oakland's Board of Commissioners and the City of Oakland over a plan to rename Oakland Airport.

The commissioners voted last week to approve the name change to the rather cumbersome and confusing San Francisco Bay Oakland International Airport — a move that San Francisco City Attorney David Chiu says is in violation of the city's trademark on the name "San Francisco International Airport."

Chiu had vowed legal action, and now, as NBC Bay Area reports, the trademark infringement suit has been filed as of today.

"We had hoped Oakland would come to its senses, but their refusal to collaborate on an acceptable alternative name leaves us no choice but to file a lawsuit to protect SFO’s trademark," Chiu said in a statement. "This new name will cause confusion and chaos for travelers, which will damage the travel industry for the entire region. We are already seeing at least one airline use the new name, indicating that SFO has already suffered economic harm."

Chiu added, "We want to see the entire Bay Area thrive as a tourist destination and expand our offerings to visitors, but the renaming is not a legal or practical way to go about it."

As the Chronicle reports, Chiu shared screenshots from the website for Azores Airlines, which flies out of Oakland, showing that a search for "San Francisco" already brings up both SFO and San Francisco Bay Oakland International Airport. The change was apparently made immediately after the board's vote last week.

Oakland port commissioners have been seeking ways to boost the profile of the airport and attract more travelers to the Bay Area to fly into Oakland. After conducting a survey last year, the board decided that the best way to raise awareness of the airport's proximity to San Francisco Bay was to put San Francisco Bay in the official airport name.

"We consistently hear from local travelers in our community about their desire for more direct flights to a wider variety of domestic and global destinations out of Oakland," said Port Commission President Barbara Leslie in a statement three weeks ago. "To make this happen, we must improve the geographic awareness among inbound travelers to the region."

And last week, following the board's vote on the name, Leslie said, "We are standing up for Oakland and the East Bay."

Critics of the plan include an Oakland environmental group called the Stop OAK Expansion Coalition. A member of that coalition, David Foecke, told the Chronicle last week that the name-change effort is a misguided attempt by the Board of Commissioners to drum up enough traffic to justify a long-planned expansion project at the airport — after several years in which traffic at the airport, particularly among business travelers, has been on the decline.

"They’re faced with the reality that they’re planning an expansion based on market demands that are not materializing," Foecke said. "So they have to find another reason to justify their expansion. Their idea about how to justify an expansion that is not the result of their own market demands, is to steal passengers from San Francisco."

San Francisco is now seeking an injunction to stop the name change from occurring.

The Port of Oakland Board of Commissioners will have a second reading of the name-change motion and take a final vote on it on May 9.

Previously: Oakland Port Commissioners Vote to Change Airport Name, Setting Up Legal Battle With San Francisco

Top image of SF City Attorney David Chiu: Photo by Justin Sullivan/Getty Images