During the Democratic debates last week, candidate Julian Castro said the crux of President Donald Trump's family separation policy at the southern U.S. border lies with an obscure portion of law, Section 1325.

The repeal of 1325 would make border crossings a civil offense, not a criminal misdemeanor.

Proponents of repealing the section argue it would ease the choice about who should stay and who should go, taking the issue out of the criminal system altogether.

On Boston Public Radio Wednesday, Juliette Kayyem argued this would solve nothing.

Family separation under the Trump administration was first authorized under Section 1325, but it continues today under a welfare policy, said Kayyem. Repealing it would not deal with myriad other issues relating to immigration, such as the conditions migrants currently face in detainment facilities; the "dreamers" who continue to live in limbo; or the wall.

"There is a fundamental, operational, legal, even philosophical debate about 1325," she said. "It was a statute passed by anti-immigrant, racist characters in the Senate in 1929, and so the question that one has to answer — which I answer in the affirmative — is, Does a country have a normative reason for wanting to promote lawful and therefore not criminal behavior, because we have a legal immigration system as everyone knows, and call the other thing criminal? I believe we do. We don't have to prosecute everyone, and we don’t. We can prioritize those prosecutions, but you want a delineation."

Juliette Kayyem is an analyst for CNN, former assistant secretary at the Department of Homeland Security and faculty chair of the homeland security program at Harvard University’s Kennedy School of Government.