A federal judge in Washington, DC, has stopped President Donald Trump from adding a new rule to the national voter registration form.
Trump wanted people to show proof of citizenship, like a birth certificate or passport, before they could sign up to vote in federal elections.
Judge Colleen Kollar-Kotelly said the president does not have the power to make this change.
The United States Constitution gives Congress and the states, not the president, the main job of setting election rules.
Because of this, the judge wrote that Trump’s order breaks the rule of separation of powers.
She also ordered the Election Assistance Commission to stop working on the citizenship rule forever.
Some states have tried similar rules before. They caused delays and confusion.
People often need many papers to prove citizenship. Married women who changed their name may need both a birth certificate and a marriage certificate.
In Kansas, about 30,000 eligible people could not register when a proof-of-citizenship rule was in place.
Democratic Party lawyers and civil rights groups called the ruling a win for democracy.
The White House has not answered questions about the decision.
Other parts of Trump’s election order, like stricter deadlines for mail-in ballots, are still being fought in court.