Summer is here – the perfect time to take a walk on a beach. But doing so is not always as simple as it might sound.

In Wisconsin, for instance, a legal case has stretched for months over whether Paul Florsheim may keep walking on a Lake Michigan beach he has walked for over 50 years.

In July 2025, Florsheim, a retired professor of public health at the university where we work, got a ticket for trespassing on a beach. The person who owns the land adjacent to the sand says the beach is a private backyard. The judge found Florsheim guilty, but Florsheim has appealed.

The case has sparked widespread discussion around the Great Lakes and raises a question hotly debated in many of the country’s coastal communities: Who is allowed on which beaches?

We are water law and policy researchers studying shoreline access in the Great Lakes region and beyond. Research shows there are many physical and psychological benefits to visiting waterside spaces. But our center’s research has found that getting to the water’s edge isn’t as straightforward as it might seem – or as many people might like.

An ancient right in modern times

A legal principle known as the public trust doctrine establishes people’s rights to use certain lands and waters.

The concept originated in Roman law and was carried through English common law into the laws of Britain’s American colonies, and on to the rest of the United States. It is well settled federal law that as states joined the union, the U.S. government transferred to those states the ownership of navigable waters and the beds beneath them, to be held in trust for all the people.

The division between those public trust areas and private land is usually set at what is called the “ordinary high-water........

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