What does this executive order do?

The Executive Order has four main policies

1) Places a 90 day moratorium on entry to the U.S. from the seven countries named in a 2015 law aimed at requiring stricter vetting for people entering from Iran or countries overrun by jihadist violence.

2) Suspends admission of refugees from any country for 120 days in order to conduct a review of the program.

3) Suspends admissions of refugees from Syria indefinitely.

4) Caps the number of refugees this year at 50,000

How does President Trump have the authority to do this?

Federal law, specifically the Immigration and Nationalization Act, gives the President pretty broad authority to block classes of immigrants from specific countries.

Here's the wording:

(f)Suspension of entry or imposition of restrictions by President

Whenever the President finds that the entry of any aliens or of any class of aliens into the United States would be detrimental to the interests of the United States, he may by proclamation, and for such period as he shall deem necessary, suspend the entry of all aliens or any class of aliens as immigrants or nonimmigrants, or impose on the entry of aliens any restrictions he may deem to be appropriate.

Why those seven countries?

The Trump administration didn't come up with these seven countries. Iraq, Iran, Sudan, and Syria were listed in a 2015 and 2016 law (The "Visa Waiver Program Improvement and Terrorist Travel Prevention Act of 2015" and its 2016 update adding Libya, Somalia, and Yemen). That Obama-era law (passed with overwhelming Democratic support) added extra scrutiny to anyone travelling into the U.S. from those countries.

These countries are either in near anarchy or have radical Islamic government. The argument is that we cannot trust these governments to provide the information needed to vet potential entrants.

Is it really a "Muslim Ban"?

That's a matter of taste.

The motivation for the ruling was clearly Islamic terrorism, and the first generation of this idea was Trump's idea to ban Muslims from entering the country. Every country listed in that 2015/2016 law is a Muslim-majority country.

But the order will stop immigrants from every religion. Anybody of any religion coming from these seven countries is barred for 90 days. Any refugee coming from anywhere — so this could be Buddhists, Jews, Atheists — are barred. Syrian refugees of any religion are barred indefinitely. The largest Muslim countries — such as Indonesia, Pakistan, and Saudi Arabia — are not covered in the 90-day ban.

Did a judge just strike down the order?

No, a judge in Brooklyn on Saturday night put a halt to one aspect of the enforcement of the EO: Federal officials stopping people who were getting off of planes today, and in at least one case, reportedly being sent back to Syria. Deporting these people has been stayed, but going forward, no judge has blocked the enforcement of the EO in terms of denying Visas to people who want to come here.

Has anything like this ever happened before?

Yes, President Obama barred Iraqi refugees for six months in 2011.

Timothy P. Carney, The Washington Examiner's senior political columnist, can be contacted at tcarney@washingtonexaminer.com. His column appears Tuesday and Thursday nights on washingtonexaminer.com.