The company, Mobilewalla, released a report in June that showed the demographics of protesters based on their location data, as BuzzFeed News first reported. “We have serious concerns that your company’s data could be used for surveillance of Americans engaging in Constitutionally-protected speech.” Warren and Sen. Ron Wyden (D-Ore.), Rep. Mark DeSaulnier (D-Calif.), and House Committee on Oversight and Reform Chair Carolyn Maloney (D-N.Y.) wrote to the company's CEO yesterday. 

They suggested that sharing the cellphone data with any government agencies may have allowed police to evade a Supreme Court ruling that requires police to obtain a warrant for cellphone data first.

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Read the full article on the Washington Post website here.