In recent weeks, airport Customs and Border Protection (CBP) agents have drawn public outcry for denying travelers US entry based on searches of their phones. The incidents have sparked concerns about phone privacy and raised questions about travelers' rights at US borders. While the Supreme Court has ruled that warrantless searches of people's cell phones violate the Fourth Amendment, there is an exception for searches that happen at the border, known as the "border search" exception.

According to the Electronic Frontier Foundation (EFF), the border search exception allows CBP and Border Patrol to search travelers' belongings, including their phones, without a warrant. This exception applies not only to the US's literal borders but also to airports, which are considered border zones. The data stored on a phone can reveal a significant amount of personal information, including financial history, medical history, and communications with doctors and attorneys, making it a significant privacy concern.

The rights of travelers to refuse a phone search depend on their immigration status. US citizens have the right to say no to a search, and CBP cannot bar them from entering the country. However, if they refuse, CBP can still take their phone, laptop, or other devices and hold onto them. Permanent residents can also refuse a search, but they may face complicating factors, such as being screened for "inadmissibility" upon returning to the country. Visa holders have fewer rights at ports of entry, and refusing a search could lead to them being denied entry to the country.

There are two types of device searches CBP officers can conduct: basic and forensic, or advanced. Basic searches involve looking at the contents of a person's phone, while forensic searches use external equipment to search the phone using advanced algorithms or to copy the contents of the phone. The government maintains that it doesn't need a warrant to conduct basic searches, but courts have imposed some limitations on advanced searches.

Some courts have been more permissive than others when it comes to warrantless forensic searches. The Ninth Circuit prohibits warrantless forensic searches unless officers are looking for "digital contraband," such as child sexual abuse material. The Fourth Circuit prohibits warrantless forensic searches unless officers are looking for information related to ongoing border violations, such as human smuggling or drug trafficking.

To safeguard their digital privacy, travelers can take precautions such as encrypting their devices, using secure passwords, and disabling biometric logins like Face ID. Travelers should also limit what can be found during basic phone or laptop searches by uploading their data onto the cloud and deleting it off their device. Backing up sensitive or personal data can also prevent others from accessing it and ensure that it's not lost if CBP seizes a phone or computer.

In a better legal environment, these precautions wouldn't be the only meaningful shield between travelers and a border search. However, until there are stronger constitutional and statutory protections, personal choices about how to configure devices and apps can only mitigate the dangers that border device searches pose to privacy and speech rights.

As the administration continues to ratchet up pressure to turn away even legal immigrants, it's essential for travelers to understand their rights and take steps to protect their digital privacy. By being aware of the risks and taking precautions, travelers can minimize the impact of phone searches at US borders.