“This report shows that an enormous number of Americans — probably without even knowing it — are handing over their full location history to shady location data brokers with zero restrictions on what companies can do with it,” Senator Elizabeth Warren told BuzzFeed News. “In an end-run around the Constitution’s limits on government surveillance, these companies can even sell this data to the government, which can use it for law and immigration enforcement.”

Mobilewalla CEO Anindya Datta told BuzzFeed that the company produced the report to satisfy its employees’ curiosity. Supposedly, Mobilewalla doesn’t plan to share info about whether specific individuals attended the protests with clients or law enforcement.

But the incident is a reminder that data brokers have access to massive amounts of data from unassuming individuals. There’s a chance that data could be used by law enforcement or be leaked — as we’ve seen happen in past data breaches. Some fear that individuals concerned about their data being swiped might avoid protests, so in effect, the practices of collecting data may suppress free speech.

At the moment, in the US, there are no federal laws preventing this type of info from being abused. Warren previously opened an investigation into government contracts held by local data brokers. Tim Cook has called for a regulatory body to oversee data brokers, and in 2018, Vermont passed a first-of-its-kind law to hold data brokers to at least some standards and to punish them for misuse. In the EU, officials have used the General Data Protection Regulation (GDPR) to go after data brokers for violating laws on personal information privacy. 

Until the US has similar regulations in place, individuals will have to piece together tools and best practices to protect their privacy.

Engadget has reached out to Mobilewalla for additional comment.