My first exposure to the electronic privacy was when Congress passed the Electronic Communications Privacy Act (ECPA) of 1986. At that time cellular and cordless telephone calls were all sent on unencrypted FM signals, similar to FM broadcast radio stations but with a narrower bandwidth. My understanding of the act came from Popular Communications magazine, which was critical of the ECPA and urged readers to lobby against it. Their view was that mobile phone providers wanted to be able to say the communications were secure. The law required radio manufactures to prevent radios sold in the US from receiving on those frequencies. The requirement that narrow-band FM receivers omit the AMPS cellular band continued long after it became outdated by mobile phones moving to other bands and digital signalling.
I always thought this rule was absurd. If you transmit radio waves that pass through my body, why can’t I or the government put up an antenna to receive those signals? The pervasiveness of mobile radio equipment that tracks our every movement, though, makes me re-think this view.
The Supreme Court dealt with these issues when it ruled last week that police need to get a warrant before placing a tracking device on a car. Five justices argue that placing a tracking device on a car constitutes a search. The other four justices argue that government using technology to track a person’s every movement, even if the person voluntarily agrees to transmit information that may allow the tracking, violates the spirit of the US Constitution’s ban on unreasonable searches.
This is a difficult point because the government is allowed to collect evidence in plain sight, including a vehicle’s movements on public roads, without a warrant. The police could secretly follow someone’s every movement, but according to four of the justices it would be illegal to do so electronically even without physical intrusion onto the suspect’s property because the technology makes “long-term monitoring relatively easy and cheap.”
In the past I rejected arguments that treat technology as fundamentally changing an existing legal concept. Often such arguments are based on fear of something someone does not understand. That is clearly not the case in this Supreme Court ruling.
It is worth reading parts of the text of the ruling, especially if you skip ahead to the two concurring judgments arguing that wrestle with the issues of what new technology means for the law.
At what point does monitoring someone electronically constitute a search?