Public opinion is quickly shifting in support of marijuana legalization of one form or another, and even one retired Supreme Court justice agrees that it's time to legalize. When asked by NPR whether it should be legalized at a federal level, retired justice John Paul Stevens — a Republican appointee who's leaned increasingly liberal — answered quickly, "Yes."

"The distinction between marijuana and alcoholic beverages is really not much."

"I really think that that's another instance of public opinion [that's] changed," he told NPR. "And recognize that the distinction between marijuana and alcoholic beverages is really not much of a distinction. Alcohol, the prohibition against selling and dispensing alcoholic beverages has I think been generally, there's a general consensus that it was not worth the cost. And I think really in time that will be the general consensus with respect to this particular drug."

Stevens, now 94, retired from the court in 2010. He's just published a book titled Six Amendments, in which he proposes six amendments to the US Constitution, some wholly new and others changes of wording — one of which could significantly limit gun rights. Stevens, of course, likely won't be involved with directly shaping federal policies toward marijuana legalization at this point, but his comments stand as yet another sign that opinion is changing, even throughout the senior ranks of government.