Demonstrators protesting Ukrainian President Viktor Yanukovych suspected their cellphone location data was being tracked since at least last week, when people in the vicinity of a clash between riot police and protesters received a chilling text message. It read: "Dear subscriber, you are registered as a participant in a mass disturbance."

The country's three cellphone companies denied they had turned over subscribers' location data or had sent the message. Instead, some suggested the "Dear subscriber" text, and others like it sent to other protestors, were the work of hackers using rogue base stations that mimicked those belonging to the carriers. Now, the protesters and civil liberties advocates around the world have cited official confirmation of the cellphone monitoring—a ruling made public on Wednesday formally ordering a telephone company to hand over such data.

From The New York Times:

Protesters for weeks had suspected that the government was using location data from cellphones near the demonstration to pinpoint people for political profiling, and they received alarming confirmation when a court formally ordered a telephone company to hand over such data. Earlier this month, protesters at a clash with riot police officers received text messages on their phones saying they had been “registered as a participant in a mass disturbance.” Then, three cellphone companies — Kyivstar, MTS and Life — denied that they had provided the location data to the government or had sent the text messages. Kyivstar suggested that it was instead the work of a “pirate” cellphone tower set up in the area. In a ruling made public on Wednesday, a city court ordered Kyivstar to disclose to the police which cellphones were turned on during an antigovernment protest outside the courthouse on Jan. 10. The order applied only to this one site on one day, and did not cover the area of the main protest, Independence Square, where sometimes more than 100,000 people have shown up, most presumably carrying cellphones whose location there could identify them as political opponents of the government.

No doubt smartphones and other types of mobile devices have made life easier for hundreds of millions of people who no longer must be tethered to landlines and computers to communicate. But handsets have also made life easier on the people who carry out government surveillance. It's trivial for someone with access to carrier servers to sift through data associated with one or more base stations and collect the unique hardware identifiers of each phone that connected to it at a given time. It's also worth remembering that the practice of collecting "tower dumps" isn't limited to eastern European countries. According to The Washington Post, a recent congressional inquiry showed that US law enforcement made more than 9,000 requests for tower dumps in 2012.

Post updated to correct name of Ukrainian president.