The kiosks are being built by a consortium that includes Qualcomm, and an Alphabet-funded company called Intersection. The system’s kiosks actually broadcast two wi-fi networks: an open network that’s just a fast, citywide version of the Internet connection at your local Starbucks, and a “private” network that encrypts all the traffic between devices and the Link kiosk. Both networks require users to input an email address to connect, but for now, only new Apple devices can access the private network.

Rolling out an ambitious municipal-wireless project in one of the world’s biggest cities is a chance for New York to establish an important standard for others to follow. But simply getting more New Yorkers online isn’t enough.

People who who can’t afford broadband access would be most likely to take advantage of a fast, free option for Internet access like LinkNYC. And since low-income communities are already among the most surveilled communities in the country, it’s particularly important that such a service offer robust privacy protections.

The LinkNYC privacy policy has already sparked some concerns at the New York office of the American Civil Liberties Union, which the human-rights organization outlined in a letter to the mayor’s office last month. Mariko Hirose, a senior staff attorney at the New York Civil Liberties Union, said the city requested input from NYCLU on the project, but that group hasn’t yet received a response to its March 16 letter.

The letter’s main concerns had to do with how LinkNYC gathers and preserves data on the users that connect to its network. The service’s privacy policy says that when users access LinkNYC networks, they agree to share information about their devices, browsing and search history, and the ways they interact with the web pages they visit. It also says that the system preserves user data for 12 months after the last time the user logs in.

But according to a spokesperson for LinkNYC, detailed browsing information is gathered only on people who are surfing the web on public Link kiosks stationed on city sidewalks. The spokesperson said that the service only gathers two pieces of information on its users: An email address (which is never verified) and a MAC address, a unique string of letters and numbers that identifies Internet-connected devices. That’s far less personal information than traditional Internet service providers and telecom services collect, the spokesperson said.

That’s true: Most home broadband providers and mobile-data providers gather and store detailed information about the sites that their users access, and will turn over that information to the government in response to a subpoena or a court order.

But that doesn’t mean an email and a MAC address alone wouldn’t be of use to law enforcement. If, for example, LinkNYC keeps logs of where and when a particular mobile device connects to different kiosks, that trail could reveal a pretty complete picture of where the device’s owner lives, works, commutes, and visits. The police could request a list of devices connected to a kiosk near a crime scene during a certain time window, and could learn a lot about the nearby devices’ owners from their connection patterns.