Normally under 8 U.S.C. sec. 1226, an immigrant may apply for release on bond or parole pending a decision on whether they are to be removed from the country, with detention becoming mandatory once there is a final decision to remove. If an immigrant is removed, then re-enters the country illegally, the prior order to remove is reinstated, that decision may not be reopened or reviewed, and the immigrant is to be deported at any time under 8 U.S.C. sec. 1231. The question in Johnson v. Guzman Chavez was whether an immigrant who was removed under sec. 1226 and then illegally re-entered the country is eligible for a bond hearing. The district court and the Fourth Circuit both held that sec. 1231 did not preclude a bond hearing.
The Court, in an opinion by Justice Alito, reversed, holding that sec. 1231 specifically applied in such circumstances, and did not incorporate sec. 1226’s detention provisions. In this case, the illegal immigrants argued that they should not be returned to their country of origin because of fear of harm, but the majority held that such a “withholding-only proceeding” did not fundamentally change the situation, nor undo the prior final order. Justice Thomas, joined by Justice Gorsuch, concurred in the result, but argued that the Court lacked jurisdiction to hear the case. Justice Breyer, joined by Justices Sotomayor and Kagan, dissented, arguing that sec. 1226 properly applied.
A link to the decision is here: https://www.supremecourt.gov/opinions/20pdf/19-897_c07d.pdf