Marijuana: A Chronic History 9 p.m., History
Hey, bud. There are about 420 reasons to watch this. Are you going to be a good doobie and tune in? This documentary is about pot, its role in the war on drugs, and the changes in its social and legal standing. The DEA perceives pot as a “gateway’’ drug, and the United States spends billions of dollars to fight its sale. Meanwhile, more than a dozen states have legalized it for medicinal purposes.
The Captains of the Final Frontier 9 p.m., Biography
“Star Trek’’ spawned six TV series and 11 movies, as well as the career of William (“$#*!’’) Shatner. This two-hour special looks at the cult beginnings of the phenomenon, focusing on the fearless captains. Those interviewed include actors Kate Mulgrew, Tim Russ, Dominic Keating, and Denise Crosby, as well as Rod Roddenberry, son of “Star Trek’’ creator Gene Roddenberry.
Modern Family 9 p.m., Channel 5
The old man (Phil) and the sea (a chirping smoke detector).
Boardwalk Empire 10 p.m., HBO
He’s. An. Or. Di. Na. Ry. Guy.
Cougar Town 9:30 p.m., Channel 5
Jules turns 42. I guess 2 is the new 7.
Border Wars 9 p.m., National Geographic
A sting in San Juan. They’re onto you, Bertrille.
The Whole Truth 10 p.m., Channel 5