Now that President Trump has handed Congress the fate of nearly 1 million illegal immigrants who arrived in the United States as minors, a key question is whether lawmakers can resolve the issues that killed the bill that would have spared them this legal limbo.

Every failure of major immigration legislation for the past dozen years can be explained by a past failure. “Comprehensive immigration reform” is a nonstarter for many conservatives because the 1986 Immigration Reform and Control Act did not deliver on its enforcement promises and did not reduce illegal immigration. (There’s a reason people still boast of the tax reform passed 31 years ago but seldom tout that year’s immigration reform.)