Anwar al-Awlaki
Anwar al-Awlaki

White House hopeful Ron Paul and the American Civil Liberties Union each condemned the United States' killing of Anwar al-Awlaki, an American citizen who has never been charged with any crime.

Paul, a staunch Libertarian, said in New Hampshire Friday that it's "sad" if "the American people accept this blindly and casually," adding that "nobody knows if he ever killed anybody," According to the Wall Street Journal. the Texas Republican lawmaker said United States officials "have never been specific about the crime."

The ACLU said the killing was a violation of both U.S. and international law.

"As we've seen today, this is a program under which American citizens far from any battlefield can be executed by their own government without judicial process, and on the basis of standards and evidence that are kept secret not just from the public but from the courts," said Jameel Jaffer, deputy legal director for the ACLU. "The government's authority to use lethal force against its own citizens should be limited to circumstances in which the threat to life is concrete, specific and imminent. It is a mistake to invest the president - any president - with the unreviewable power to kill any American whom he deems to present a threat to the country."

Added ACLU National Security Project Litigation Director Ben Wizner: "If the Constitution means anything, it surely means that the president does not have unreviewable authority to summarily execute any American whom he concludes is an enemy of the state."

As the Washington Post reported in January 2010, the Obama administration has elected to continue a post-Sept. 11 Bush administration policy authorizing the CIA and the military to kill U.S. citizens outside the country if there is strong evidence of their involvement in terrorist activities. U.S. officials reportedly maintain lists of citizens who they have the authority to kill. Awlaki's father unsuccessfully sought a court order last year to keep the government from killing his son.

al-Awlaki is a radical Islamic preacher who rose to the top ranks of al Qaeda in Yemen, and U.S. officials said he played a "significant operational role" in plotting and fomenting attacks on the country where he was born. "He directed the failed attempt to blow up an airplane on Christmas Day in 2009, he directed the failed attempt to blow up U.S. cargo planes in 2010, and he repeatedly called on individuals in the United States and around the globe to kill innocent men, women and children to advance a murderous agenda," President Obama said Friday.

The Obama administration's position that it can kill a U.S. citizen without due process seems to stand in contrast to its handling of foreign-born terrorists like Khalid Sheikh Mohammed, who are provided access to lawyers and who the administration maintains should be tried in federal courts.

Ron Paul was not the only presidential candidate to raise questions about the killing. Gary Johnson, who shares many of Paul's libertarian beliefs, said "we cannot allow the War on Terror to diminish our steadfast adherence to the notion of due process for American citizens. The protections under the Constitution for those accused of crimes do not just apply to people we like -- they apply to everyone, including a terrorist like al-Awlaki. It is a question of due process for American citizens."