My Martin Luther King Day interview on Fresh Air today is with legal scholar Michelle Alexander, whose book has a provocative thesis: that the mass incarceration of African Americans associated with the war on drugs has created a new caste system in America.

Alexander says millions swept up in the drug war, even those who avoid lengthy prison terms, are forever branded as felons and denied basic rights and opportunities which would allow them to become productive, law-abiding citizens.

Her book is called The New Jim Crow: Mass Incarceration in the Age of Colorblindness.

Others have noted the debilitating effect of so much imprisonment among families and communities of color.

Alexander's book explores what she calls "the racial ideology that gave rise to (the drug) laws." She says they were driven by a Republican strategy to appeal to alienated white voters in the South, and politicians found it effective to play on fears of black crime.

Alexander writes that mass incarceration has "emerged as a stunningly comprehensive and well-disguised system of racialized social control that functions in a manner strikingly similar to Jim Crow."

To reverse the damage, she writes, we have to have a conversation about race and attack the public consensus that "drug crime in this country is understood to be black and brown."

I questioned some of the premises in her case in our interview, and it makes for an interesting hour of listening. You can hear it at 3 and 7 Monday on WHYY, and of course you can listen, download, or get more information at the Fresh Air website.