The 9/11 attacks, and the desperate efforts to prevent a repeat, have forced the United States into a series of moral choices it didn't want to make and, for the most part, had hoped to avoid.

Nonetheless, as a matter of official and unofficial policy, we embraced the concept of pre-emptive wars; in the case of Iraq, it was declared on the flimsiest of grounds. Vital constitutional protections were selectively suspended (such as indefinite detention without right to trial).

Traditional safeguards of privacy were overruled by the Patriot Act. Targeted assassinations -- extrajudicial killings, if you will -- and "enhanced interrogation techniques" amounting to torture became part of our anti-terrorism arsenal.

These policies originated in the George W. Bush administration. Candidate Barack Obama's 2008 campaign rhetoric led many supporters to believe he would abandon or soften many of the policies.

However, with a few exceptions where Congress thwarted him -- closing the prison at Guantanamo Bay, Cuba, and trying its inmates in civilian criminal courts -- President Obama not only embraced Bush-era surveillance and anti-terrorism policies, he expanded on them.

One such expansion has just come to light: an internal Justice Department memo saying it is legal for the administration to kill U.S. citizens abroad if an American is a senior member of al-Qaida or an allied terrorist organization and is believed to pose an "imminent" threat of violent attacks against other Americans.

The memo appears to be justification for continued lethal drone attacks and a belated legal rationale for the 2011 drone strike in Yemen that killed two Americans: Anwar al-Awlaki, 40, who preached a virulently anti-U.S. version of jihad; and Samir Khan, the 25-year-old publisher of a how-to terrorism magazine.

No one outside radical Islamic circles seems to have mourned their passing, and it can be convincingly argued that we were justified in killing them before they incited followers to begin killing some of us.

But we are a nation of rights and laws, and this memo is distressingly broad about the process of selecting Americans to assassinate. The memo says that an "imminent threat" need not be based on any specific information and that certain al-Qaida leaders are acceptable targets, on the grounds that al-Qaida leaders are always and continually plotting against the United States.

News accounts, reflecting the memo, are vague about who exactly can order a strike, referring to "an informed, high-level government official" or simply a "decision-maker." And the memo says these projected assassinations should not be subject to judicial review; thus, the decision would solely be the prerogative of somebody in the executive branch.

Not surprisingly, 11 senators who will weigh in on Obama's nominees to the Pentagon and CIA have demanded to see the secret legal memos supporting the conclusions in the Justice memo that became public.

There remain many, many questions to be answered before targeted killings, basically on one person's say-so, become official U.S. policy.