美国有线新闻 CNN 奥巴马移民行政令进入审议环节（在线收听）

play pause stop mute unmute max volume 00:0003:11repeat repeat off Update Required To play the media you will need to either update your browser to a recent version or update your Flash plugin. AZUZ: The U.S. Supreme Court is now hearing arguments in a case related to President Obama's controversial executive action on immigration. The president denounced the action in 2014. It allows millions of people who are in the U.S. illegally to stay without the threat of being deported.

They could apply for work programs and other benefits, as long as they paid taxes.

Twenty-six states sued the government over this. The Obama administration says its action is legal, and like those of previous presidents on immigration. But no executive action has ever impacted this many people before. And executive actions don't go through Congress. Critics say this one in particular should.

Another aspect to this — the Supreme Court is divided. Four of the justices were appointed by Republican presidents, four by Democratic presidents.

Conservative Justice Antonin Scalia died suddenly in February and his potential replacements have been held up in Congress. So, if the high court rules 4-4 on this issue, the ruling of the lower court stands, and that court blocked the president's action on immigration.

This isn't the only debate happening right now on this issue.

REPORTER: H-1B sounds like an airplane, or an exotic disease. They're actually visas and these visas are one of the most controversial parts of the immigration debate. Huge tech giants like Facebook and Google call them essential to their business, but critics say companies are exploiting them at the expense of the American worker.

So, what exactly are the H-1B visas?

Congress created them in 1992 to bring in highly educated and specialized foreign workers into the country.

GEORGE H.W. BUSH, FORMER U.S. PRESIDENT: This bill provides for vital increases for entry on the basis of skills, infusing the ranks of our scientists and engineers.

REPORTER: They're supposed to fill shortages — think computer programmers, engineers, doctors.

Around 85,000 are allotted a year and they last up to six years, plus a possible extension. To get one, you have to be educated. Ninety-nine percent of H-1B workers have at least a bachelor's degree and over a half have advanced degrees.

So, why are H-1Bs are controversial?

Well, critics claim the companies aren't using them to fill shortages. They say the companies are actually bringing in foreign workers so they can pay them less than American workers, and it wasn't mean to work this way.

To protect American workers from exactly what critics are accusing the companies of doing now, the law was set up to require a, quote-unquote, "prevailing wage". That's a number calculated for each job by the Department of Labor. But critics say that that number, it's rife for loopholes and abuse.

Another problem for, quote-unquote, "specialized hard to fill jobs" sometimes aren't. Around 50 percent of H-1Bs are going to computer programmers, but they've also been used for sports coaches, ranch workers, preschool teachers.

And it's not just American workers who can be hurt by their misuse. Employers hold incredible leverage over H-1B visa holders. Some have described the workers as indentured servants because an H-1B worker needs to have a job to stay in the country. Complain about working conditions?

You could lose your jobs and be forced to leave the country.

So, here we are, tech companies want more H-1Bs, critics want reform. Will Silicon Valley get its way?