Since Padilla had joined the terrorist organization al Qaeda and engaged in warlike actions against the armed forces of the United States in Afghanistan, the Judges said in concurrence with the Government, the President possessed an authority to designate Padilla an "enemy combatant." The issue sparked a controversy and intense debate among lawyers and other observers. One of the complications of the case was the position taken by Padilla's lawyers. Padilla's lawyers did not contest the charges the government had leveled against Padilla. Instead, the lawyers argued that even if everything the government said about Padilla was true, the U.S. President did not possess the authority to detain a U.S. citizen without trial. The Fourth Circuit interpreted the position of the lawyers as if the lawyers agreed that the charges leveled against Padilla were true. The lawyers rejected this interpretation. The Government allegations against Padilla were contested by independent observers, including the American Civil Liberties Union. Initially, the Government alleged that Padilla had plotted to explode a "dirty bomb" but then abandoned that charge,...

The issue became even more complicated and contentious as the Fourth Circuit grounded its decision on Padilla's activities in Afghanistan. One of the charges leveled against Padilla was that he was in possession of an assault rifle when he was detained in Afghanistan-Pakistan border, but given the dangerous nature of the environment there, it is hardly surprising that Padilla was armed with an assault rifle (Steinberg). Padilla was eventually transferred to Miami and sentenced with seventeen years and four months of prison based on charges of criminal conspiracy against the U.S.
References

BRIEF of the CATO INSTITUTE as AMICUS CURIAE in SUPPORT of RESPONDENTS, available at ;

"Padilla v. Hanft," Statement by the American Civil Liberties Union, November 30, 2006 available at ;

Padilla v. Hanft, 423 F. 3d 386 - Court of Appeals, 4th Circuit 2005, available at ;

Steinberg, Michael (2005). "Padilla v Hanft: A Very Dangerous Decision," Monthly Review, 9 September 2005, available at ;