Employment verification. The 1986 law didn't prevent illegals from getting fake identification. Americans on both left and right hated the idea of anything like a national identity card.
Americans today feel differently. Most of us seem content to carry cellphones that enable others to track our whereabouts at any time.
And we have the E-Verify system for employers to check the legal status of job applicants. It's working well after initial glitches; and in states with high E-Verify usage, like Arizona, illegal numbers have declined.
It could be even more effective to require identity cards with biometric links. Making it hard for illegals to get jobs would hugely reduce the incentive for illegal immigration.
Source of illegal immigrants. Nearly 60 percent of illegal immigrants come from Mexico, with which we share a 2,000-mile border. But net migration from Mexico appears to have been zero since the housing bubble burst in 2007.
We don't know whether it will resume again. But we do know (as we didn't in the decade after our free trade agreement) that Mexico's economy can grow faster than ours, as it is now.
Mexico is becoming a majority middle-class country, which reduces incentives to emigrate. I predict we'll never again see Mexican immigration of the magnitude we saw between 1982 and 2007.
If that's right, it means we won't see a wave of illegals as we saw after the 1986 law.
There were potentially significant differences between what Obama and Rubio said yesterday.
Obama wants a faster path to citizenship for illegals. Rubio insists that legalization only be triggered when enforcement is strengthened.
Putting together a comprehensive bill requires trade-offs and compromises. Obama's 2007 Senate votes for what John McCain and Edward Kennedy called killer amendments helped defeat an immigration bill when the political stars seemed more in alignment than they do today.
Obama now could demand provisions Republicans won't accept and blame them for killing reform. It depends on whether he wants a political issue or a law.