Ashcroft v. Al-Kidd
Justice Antonin Scalia wrote a majority opinion.  He was joined by Chief Justice John G. Roberts and Justices Anthony Kennedy, Clarence Thomas, and Samuel Alito.  Scalia wrote that a Magistrate Judge had issued a valid arrest warrant for al-Kidd based on specific information about him.  Al-Kidd was not arrested in a general effort to sweep a large group of Muslims into jail  he was specifically arrested because he was suspected.