Politicians are using mortgage data against their enemies, so it’s time to figure out how much of it is available and what law-abiding citizens can do to shield it from prying eyes.

On Monday, President Trump said he was removing Lisa Cook from the Board of Governors of the Federal Reserve. He has accused her of declaring both of her homes as her primary residence, which can be a form of mortgage fraud given that interest rates are often higher for vacation homes or investment properties. On Tuesday, her lawyer said she would sue over her dismissal.

Bill Pulte, the director of the Federal Housing Finance Agency, who asked the Department of Justice last week to investigate Ms. Cook, suggested this week that she wouldn’t be the last person to face such charges.

“There is too much mortgage fraud in Chicago,” he said on social media, calling out the city where Mr. Trump has threatened to send troops. Mr. Pulte also asked for tips on fraud from the public.

Ms. Cook also wasn’t the first public figure to come in for this scrutiny. Other Trump adversaries, including Letitia James, the attorney general of New York, and Senator Adam Schiff, Democrat of California, are facing similar inquiries. The Texas attorney general, Ken Paxton, a Republican, has also had to answer for his housing records.

It wouldn’t be hard for self-styled detectives to try to uncover fraud or just pry into people’s finances. While rules vary by locality, at least some mortgage data is part of the public record in most places.