Border phone searches are in the news a lot lately. Last month, a French scientist was allegedly blocked from coming to a conference in Houston after U.S. Customs and Border Protection (CBP) found statements against President Donald Trump on his phone. A few days later, Brown University doctor Rasha Alawieh was turned away at the airport after CBP allegedly found pro-Hezbollah images on her phone.

How does CBP have the power to rummage through phones so easily? After all, ordinary police can't just stop you on the street and search your phone without a warrant. But courts have recognized a border exemption to the Fourth Amendment, allowing the government to conduct routine anti-smuggling searches of travelers. Although some lower courts have weighed in on whether that exemption applies to personal electronic files, there's no definitive ruling yet on phone searches at the border.

Until the Supreme Court rules on the issue, CBP officers are mostly limited by the agency's own internal regulations. The regulations allow officers to conduct a "basic search" (flipping through the phone by hand) at their discretion, and require "reasonable suspicion" or a "national security concern" to conduct an "advanced search" with forensic phone hacking software such as Cellebrite. The regulations also restrict officers to searching what's already on the phone, not downloading new data, so phone searches should be conducted in airplane mode or otherwise disconnected from the internet.

Of course, an agency pinky-swearing not to violate your rights is not worth much in the way of practical protection. The Electronic Frontier Foundation (EFF) and the American Civil Liberties Union (ACLU) have both put out guides for protecting electronic privacy at the border. Reason spoke to Sophia Cope, senior staff attorney at the EFF, and Nathan Wessler, deputy director of the ACLU's Speech, Privacy, and Technology Project, about the nitty gritty of defending your data.

There are a few basic tips that people should know but often don't. The U.S. government cannot prevent Americans from reentering the country no matter what. Nor can it compel anyone to give up their passwords. (The cops can force you to open a Face ID or fingerprint lock, though.) And shutting down an iPhone makes it much harder to break into. Other aspects of border privacy require more careful consideration.

The bottom line? Prospective travelers "need to have a plan about how to protect their data, and what they are going to do if they're pulled into secondary inspection and asked to unlock their device," Cope says. "You cannot be in secondary inspection like, oh crap, what am I supposed to be doing? That's the most important thing. The second most important point is that one size doesn't fit all."