Breathalyzers, 'textalyzers' and the Constitution

New York's Legislature is considering a proposal to give police officers "textalyzers," gizmos that would enable roadside checks of drivers suspected of using mobile phones behind the wheel. Given the dangers of texting while driving, the technology may be a good idea. But is it constitutional?

The answer requires looking at two issues. One is the constitutional status of smartphones. The Supreme Court unanimously held in 2014 that the police need a warrant to search a phone. That implies that using a textalyzer without a warrant would be unconstitutional.

The second issue is the comparison between the textalyzer and the Breathalyzer. Under current law, states can take a driver's license away from someone who refuses to take a Breathalyzer sobriety test, which measures alcohol levels in blood circulating through the lungs. Just last week, the Supreme Court heard arguments about whether a state can also make it a crime to refuse the breath test - and it seemed to think it could.

So which is more intrusive: checking your phone or checking your body chemistry?

Start with the textalyzer itself. Reportedly, the technology will come from the Israeli firm Cellebrite, which makes a product that can be used to pull data from a smartphone at roadside.

The proposed textalyzer supposedly wouldn't scrape the content off your smartphone -- that would require a warrant under the Supreme Court's 2014 ruling. The device would be programmed instead only to check whether the phone had been recently used.

But the fact that the textalyzer is derived from more powerful technology might make the justices nervous about whether a search is actually taking place. The textalyzer would presumably have to look at all your apps to ascertain whether you had been using one while driving.

Since there are plenty of app uses that are permissible while driving -- such as listening to music or GPS directions - the textalyzer would have to evaluate the content of what you did on the app. If you were just listening, that would be fine. But if you altered your destination, that would probably count as texting while driving. The upshot is that the textalyzer probably would need to assess the content on your phone use to some degree.

The justices might also worry about the slippery slope. Once the police have your phone in their hands, will they really be able to stop themselves from searching it?

A related problem is whether you would have to unlock your phone for the textalyzer to work. If the answer is yes, then that would already seem to violate the court's ruling. The Federal Bureau of Investigation found a way to unlock the San Bernardino terrorist's iPhone, so maybe you wouldn't have to unlock your phone yourself.

But it's not much better if the government breaks in.

All this suggests that the court might find the textalyzer to be a search tool, in which case a warrant would be needed to use it.

Even if the court differentiated the textalyzer from a full phone search, however, there's still the question of how it compares to the Breathalyzer, legally speaking.

Intuitively, it seems to me that it's more invasive to check the level of alcohol in your blood than it is to check your phone. I know studies say that most of us keep our mobile devices within arm's reach 21 hours a day. But hey, I try to keep my blood inside me the whole 24.

What's intriguing is that when the justices considered last week whether the states could criminalize the refusal to take a Breathalyzer test, the oral argument seemed to suggest they didn't consider the search unduly invasive. Justice Stephen Breyer pointed out that "what you breathe" into the Breathalyzer "is carbon dioxide, which is going to go into the environment anyway; you're not going to keep it."

For the record, I think that Breyer's comment misses the point, which is that the air you breathe out is being used to measure the level of alcohol in your blood, which stays inside you. For my money, a Breathalyzer test is a search. But I'm not the court.

If the court holds that breath testing isn't searching, could it later say that checking whether you've texted is more invasive? That would create an apparent contradiction. So a pro-government holding in the Breathalyzer case would be good news for the textalyzer.

My conclusion is that textalyzer searches ought to be held unconstitutional without a warrant - but in practice, there would be room for the Supreme Court to treat it as less than a search.

In the real world, a lot will turn on how dangerous the court considers texting while driving, and how limited the textalyzer technology is.

The justices l seemed ready to stop states from making it a crime to refuse a warrantless blood test while allowing them to force a Breathalyzer test. They're worried about drunk driving and consider breath sampling noninvasive. If they feel the same way about distracted driving and the textalyzer, they might well allow it.

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Noah Feldman, a Bloomberg View columnist, is a professor of constitutional and international law at Harvard University and the author of six books, most recently "Cool War: The Future of Global Competition."