"They've been very, very effective in the war on terror," the former George W. Bush appointee told CNN's "New Day." "It's a wonderful technology."
Two key decisions would be involved -- whether to put an American on a kill list and whether to execute on the kill order, said Gonzales, who is now in private practice with a law firm in Nashville.
"As to the second, I think the president has the authority -- as the commander in chief -- once you identify where an 'enemy combatant' is, to take action, to take him out on the battlefield like you would any other enemy," he said.
Due process would be a concern only in designating someone as an "enemy combatant," he said.
Once that decision has been made, "then the commander in chief should be able to execute on that order at the moment of his choosing, because you never know when you might locate that individual -- you might only have minutes, you might only have hours."
But the administration has reportedly taken months to decide whether to target someone, a pace that might wind up working against it, Gonzales said. "I think the courts are going to ask, if they finally take up this issue, you have months to make this determination, why isn't there more due process given to the individual, to the American citizen?"
Americans targeted before
The United States has targeted an American before, most notably Yemeni-American cleric Anwar al-Awlaki, a key member of al-Qaida in the Arabian Peninsula killed by a U.S. drone in 2011.
Another American, Samir Khan, was killed in the same strike, though he was not the target of the operation. Khan was behind al-Qaida's English-language Inspire magazine, which aimed to influence jihadis and wannabe jihadis around the world.
"What I would worry about is that the courts have seemed to indicate that, when you're talking about the rights of American citizens, there are certain due process considerations that have to be taken into account before you designate someone as an enemy combatant," Gonzales said.
"I would have advised the president that Al-Awlaki is an enemy combatant and, Mr. President, you do have the authority to take him out in a drone strike, but I would also caution that, given recent Supreme Court decisions, I'm not sure there are five votes on the court that would agree with that assessment."
Gonzales, who supported the Bush administration's policies that many derided as torture, said Congress' continued funding of anti-terrorism efforts "indicates tacit agreement that the war on terror can continue, and that these kinds of actions are in fact lawful." He noted that Congress gets periodic briefings on such matters and "apparently has no issues, no major problems with these kinds of tactics."
Asked whether drones might be used to kill Americans who have been determined to be pressing, imminent threats to U.S. safety on U.S. soil, Gonzales said doing so was probable, even though it might worry civil libertarians.
"It's very likely that we're going to confront more terrorists here in this country; it's very likely they are going to be American citizens. And if, in fact, this is an effective technology, why wouldn't you use this technology to eliminate this threat?"
ACLU says government abusing power
The American Civil Liberties Union contends the administration abuses its power, particularly when it comes to drone strikes.
"Even in the context of an armed conflict against an armed group, the government may use lethal force only against individuals who are directly participating in hostilities against the United States," the group says on its website. "Regardless of the context, whenever the government uses lethal force, it must take all possible steps to avoid harming civilian bystanders. But these are not the standards that the executive branch is using."
Unofficial estimates based on reports by human rights groups and media accounts indicate the Obama administration has carried out hundreds of drone strikes that have killed hundreds and perhaps thousands of people, including civilians, in an escalation of the practice the Bush administration started.
Most have occurred in Afghanistan, but others have taken place in countries with no ground war, including Yemen, where al-Awlaki and two other Americans died in 2011.
Critics say the government oversteps the legal boundaries of the Constitution and international law, particularly by making decisions on targeted killings in secret without going before any court.