U.S. Rep. Kevin Mullin found green card holders detained for days inside a federal facility at San Francisco International Airport after two unannounced oversight visits.

SFO sits at Burlingame's eastern border, and Mullin's CA-15 district office is in San Mateo. He is believed to be the first federal lawmaker to conduct an oversight visit of a U.S. Customs and Border Protection (CBP) airport detention facility.

CBP officials turned Mullin away on his first attempt Aug. 20, according to the San Francisco Chronicle. The agency later apologized, acknowledging it had "intentionally, but mistakenly" denied his entry, according to Mullin's office. Mullin returned Wednesday, Aug. 26, and was allowed inside.

The facility, called the "in transit lounge," is a 3,000-square-foot room in the Dianne Feinstein International Terminal. Mullin found couches lining the perimeter, lounge chairs, tables and restrooms. Five people were detained. CBP officers were present in the room, with additional officers watching from an adjoining observation room through a two-way mirror. A stack of pillows and blankets sat in a corner. One person was asleep on a couch.

CBP told Mullin the lights are rarely turned off at night. Detainees get three meals a day from airport food vendors but cannot contact lawyers. They can occasionally ask CBP to reach a family member. Detainees can access prescription medications only if the medications are in pharmacy-labeled containers bearing their name.

"There's no way I'd want to stay in that congregate setting for a night, let alone a whole week," Mullin told the Chronicle.

CBP confirmed to Mullin that the agency is holding lawful permanent residents for multiple days while awaiting certified court records. Agents said the practice of holding people rather than releasing them began early in 2025 under the Trump administration. Green card holders returning to the U.S. have been flagged for past arrests or convictions, including decades-old, non-violent misdemeanor charges and expunged cases.

The Chronicle's investigation documented more than 25 cases of people held at SFO beyond CBP's own 72-hour guideline through July. Nineteen of those 25 held green cards. Nationally, federal data shows CBP has detained more than 400 people at airports for longer than 72 hours since January 2026, including 146 green card holders. SFO had the second-highest number of extended detentions resulting in transfers to U.S. Immigration and Customs Enforcement (ICE), behind Miami. Mullin later thanked the Chronicle for its "in-depth investigative reporting" in a post on X.

CBP did not respond to the Chronicle's detailed questions about the facility, though a spokesperson said the agency treats travelers "fairly and with dignity," the Chronicle reported.

The detention facility and customs areas at SFO are operated exclusively by federal officials, not the airport or the City and County of San Francisco. SFO spokesperson Doug Yakel told the Chronicle that the Department of Homeland Security (DHS) has extensive regulatory authority over U.S. airports and that CBP facilities fall outside airport jurisdiction.

On Tuesday, Sept. 1, Mullin spoke with San Francisco Mayor Daniel Lurie about the visit. Lurie reiterated the city's commitment to local officials not participating in federal immigration enforcement, according to Mullin's office.

Mullin said he plans to continue oversight visits but has not announced a specific next step or hearing date.