Judge Nina Morrison of the US District Court for the Eastern District of New York (Brooklyn, Queens, Staten Island, and Long Island) has ruled that police, including officers of U.S. Customs and Border Protection (CBP), need a warrant to search your cellphone at JFK International Airport, even when you are entering or leaving the US.

This ruling is certainly a positive development. It's a break with a line of judicial decisions that have made US borders and international airports a Fourth Amendment-free zone, even for US citizens. It's likely to influence other judges and other courts, even though — as a ruling from a District Court rather than an appellate court — it doesn't set a precedent that's binding even on other judges in the same Federal judicial district.

But there are important issues that weren't addressed in this case, and important things you need to know to exercise your rights at JFK or other airports — even if judges in future cases in the same or other judicial districts are persuaded by the ruling in this case.

While Mr. Kurbanali Sultanov, a US citizen, was visiting his family in Uzbekistan in early 2022, an "alert" was added to the Department of Homeland Security's TECS database flagging  him for special treatment whenever he tried to enter or leave the US.

A check for TECS "lookouts"  is one of the components of the algorithmic ruleset used by CBP to determine, from each international airline reservation (PNR), whether or not to give the airline permission to issue a boarding pass to that passenger for that flight and what instructions or messages to send to CBP staff or other Federal agencies as to how to treat that passenger when they arrive at an international airport or US border crossing. TECS alerts can be generated by matches with one or more fields including name, date of birth,  passport number, telephone number, email address, IP address, and/or other identifiers and selectors.