In light of these concerns and what we now know about the "skills shortage," is there any way to justify expanding H1-B?

Possibly, but only with caution.

The Benefits of High-Skill Immigration

Hollow rhetoric about our unskilled workforce aside, there are a few compelling arguments in favor of H1-B. First, and most simply, it's reasonable to think that companies should be able to quickly and easily fish for talent abroad in the cases where it's truly necessary.

Moreover, there may be evidence that the H1-B program has been a net plus for American workers. Earlier this year, U.C. Davis's Giovanni Peri and Colgate's Chad Sparber released a draft paper suggesting that that from 1990 to 2010, the influx of H1-B workers actually accounted for an astounding 10 to 20 percent of yearly U.S. productivity growth, and added $615 billion to the economy. That, they say, boosted both wages and employment for U.S. born scientists and engineers. There were undoubtedly winners and losers; while average salaries rose, some older Americans almost certainly gave up their jobs to younger immigrants with fresher skills. But if the paper is right, that price seems worthwhile in the grand scheme of things.

Finally, over the long term we really do want more immigration. Economies grow essentially one of two ways: productivity growth, or population growth. H1-B helps with the latter. It obviously is not a perfect tool for the job (after all, it's technically supposed to be a "non-immigrant" visa). It would be far better if we simply handed skilled workers more green cards -- and to be fair, the immigration bill is designed to do that as well -- since that gives them the freedom to shop around for jobs, bargain for higher pay, and set down roots in a community. But inviting in a group of educated, decently paid, law-abiding professionals who might one day become permanent residents through employer sponsorship or through marriage isn't a terrible second option.

A Policy Compromise

So perhaps a compromise is in order. Today, the the number of generic H1-B visas available to for-profit companies is capped at 65,000, with another 20,000 set aside for foreign students who earn an advanced degree at U.S. universities.* The Senate plan would give those numbers an MLB-sized shot in the arm. The cap would jump to 110,000 visas minimum, but could go as high 180,000, based on a formula that would account for both demand from employers and the unemployment rate for skilled professionals. Another 25,000 visas would be around for advanced degree earners.

This is too much, too fast for program that's such a mixed bag in its present state. Instead of rushing to bulk it up, Congress should just make the system more flexible by leaving the cap at 65,000 and carefully indexing it to health of the job market (the current formula could probably use some tweaking). That would give it room to grow without creating a sudden surge of new guest workers into an economy that may not be primed to handle them.