Internet access is getting faster and cheaper by the year. Four out of five households in developed countries now have home Internet connections. But a home connection is still out of reach of many in the United States. People in major American cities pay more for basic broadband speeds than city-dwellers abroad. Fewer than half of Americans who make less than $20,000 a year have broadband access at home, and the number-one reason that Americans give for not having broadband at home is that it’s too expensive.

That’s the problem New York City is taking on with LinkNYC, a program launched in February that aims to bring free, fast wireless service to the city’s millions of residents. New York isn’t the first place to offer a free municipal wi-fi network, but LinkNYC is designed to be the fastest and most wide-reaching such project in the country when it expands to cover the whole city in the next 10 years.

The system takes advantage of the infrastructure behind New York’s now-outdated pay phones. Touchscreen kiosks are sprouting up where the iconic phones used to be, and will eventually number in the thousands. The kiosks function as public Internet terminals, free Internet phones, and access points for the citywide wi-fi network.

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.

It’s too early to know if that could happen, because LinkNYC service is still in its first months of operation. The spokesperson said that the program hasn’t yet received any government requests for information, and couldn’t say what specific information would be available for production in response to a legal request from law enforcement.

LinkNYC “would require a subpoena or similar lawful request before sharing any data with the NYPD or law enforcement, and we will make every effort to communicate government requests to impacted users,” said Jen Hensley, the program’s general manager, in a statement.

Hirose, the NYCLU staff attorney, said it’s encouraging that LinkNYC doesn’t intend to collect browsing data on its wi-fi users, but stressed the importance of reflecting that fact in the official privacy policy. “There are people for whom this will be their way to connect to the Internet,” Hirose said. The essential nature of Internet access creates an power imbalance that could leave those people vulnerable, so she said she hopes people will push for more protective privacy rules.

In rolling out a huge public network, LinkNYC had to attend to a huge range of security and privacy issues. Those challenges are clearly on their minds: The program’s CTO, Colin O’Donnell, told The Verge about the network’s security protections, which aim to keep malware out of the system.

The encrypted private network, too, is a very important feature that will make browsing safer for the system’s regular users. The fact that it’s currently only available on newer, higher-end Apple devices leaves the security feature out of reach of those who need it most, but LinkNYC says they’re working to bring it to more devices soon.

When its rollout is complete, New York’s municipal wireless system will be a boon to all sorts of users. But since the low-income communities don’t have as much bargaining power as the rest of the city, it’s important that the network be designed to keep those vulnerable users as safe as possible. If New York can navigate that successfully, and keep the municipal wi-fi network from becoming another tool for surveillance, then it could provide a model for smaller cities that might not have the resources to start a citywide network project from scratch.