F.B.I. agents arrested on Friday a Milwaukee judge accused of obstructing justice by directing an undocumented immigrant out of her courtroom through a side door while federal immigration agents waited in a hallway to arrest him.

The arrest of the judge, Hannah C. Dugan, quickly drew condemnation from Democratic leaders and prompted protests in the Wisconsin city.

But the U.S. attorney general, Pam Bondi, defended the move, saying Judge Dugan’s arrest sent a “strong message” to judges that the Trump administration will prosecute them if they obstruct justice by “escorting a criminal defendant out a back door.”

And after the arrest, the F.B.I. director, Kash Patel, posted a photo of her in handcuffs on X, adding, “No one is above the law.”

The arrest has raised several questions — many of which remain unanswered. Here’s what we know so far.