Patrick Kennedy, one-time member of Congress and lifelong member of the Kennedy clan, will appear on The Colbert Report on behalf of an anti-marijuana-legalization group. Which is pretty ironic, given Kennedy's drug-related arrests.

When Kennedy left Capitol Hill after serving the state of Rhode Island until 2011, he helped found SAM — Smart Approaches to Marijuana. It's on SAM's behalf that he'll make his Colbert appearance, almost certainly arguing that pot should not be legalized for the myriad reasons listed on its website: marijuana would be used more, incur more in "social costs" than it brings in from taxes, and increase arrests and incarcerations.

All of these points are debatable and have been debated, but that last point is worth pulling out. "Under legalization, more people, not fewer, will be ensnared in the criminal justice system," SAM argues, because alcohol "is responsible" for more arrests than for illegal drugs. And: "People are not put in prison for small time marijuana use today," because only 0.7 percent of all inmates in state institutions are there for marijuana possession.

Alcohol is responsible for a lot of arrests in part because drunk people do stupid things. And saying that people are not put in prison because only 1 in 140 prisoners is there for marijuana possession seems a little slick. (And the numbers on this vary.)

But here's the thing: those arrests vary widely based on race and class. Which Kennedy should recognize. When he was arrested for driving under the influence of prescription medications after crashing his car in Washington, D.C. in 2006, Kennedy — a wealthy white man — avoided jail time. He later admitted that he was addicted to Oxycontin at the time of the accident, and was also an alcoholic.

Had Kennedy not been a member of Congress named Kennedy, if he'd been arrested with pills in hand as opposed to in his blood, the results could have been different. They certainly are for marijuana users; according to research conducted by the ACLU, black Americans were four times more likely to be arrested for marijuana crimes in the United States in 2010. Kennedy's career wasn't sidelined by his abuse or his arrest. That ACLU report describes people of color arrested with small amounts of illegal drugs whose lives were ruined by the punishments they faced for recreational use no different than Kennedy's.

There's another level of irony that can't be ignored. Kennedy's grandfather, Joseph P. Kennedy, was long rumored to have made some portion of his family's massive fortune in bootlegging liquor during Prohibition. A biographer of the elder Kennedy argues persuasively against the rumor, but admits that Kennedy had the foresight to ship whiskey from Scotland into America prior to the repeal of the law, using "medicinal liquor permits" to make his storehouses of booze perfectly legal. When repeal happened, Kennedy was ready to open the taps.

Maybe Kennedy wasn't making his own booze. But he was poised to recognize the business and social benefits of relaxing opposition to alcohol — and largely made the Kennedy name and position on that foresight. Had Joe Kennedy not been eager to see Prohibition repealed, his grandson could have suffered a much different fate if arrested for driving under the influence of illegal narcotics decades later.

Something to keep in mind as he tries to make jokes with Stephen Colbert.