Confusion has reigned since U.S. President Donald Trump signed his executive order restricting entry into the United States for nationals of seven predominantly Muslim countries.

Story updated to February 6, 2017, the day after U.S. District Judge James Robart put a nationwide hold on Trump’s executive order. On March 6, 2017, Trump signed a another executive order for a new travel ban starting on March 16. will be following this ongoing story and the immigration implications.

As of February 6, here are answers to common questions your clients might have.

Who cannot enter the U.S.?

According a U.S. Customs FAQ page, the entry ban applies to “nearly all travelers, except U.S. citizens, traveling on passports from Iraq, Syria, Sudan, Iran, Somalia, Libya, and Yemen who are applying for entry to the United States at any port of entry—air, land or sea.”

Can Canadians with citizenship from one of the seven countries enter the U.S.?

If they’re Canadian citizens: Yes. Henry Chang, partner at Blaney McMurtry LLP in Toronto, says dual citizens must travel using their Canadian passports.

Canadian permanent residents: Yes, but only for non-refugees, and under two conditions:

  1. travel must originate from within Canada, and
  2. the traveller must undergo pre-clearance in Canada by a U.S. customs and border officer prior to entering the U.S. For people crossing a land border, this will happen at one of the land ports of entry (e.g., the Ambassador Bridge in Windsor/Detroit). For people flying into the U.S., pre-clearance must take place at the departure airport.

Here’s what the FAQs say: “Landed immigrants of Canada (not including refugees) who hold passports of a restricted country can apply for admission to the United States, if the individual presents that passport with a valid immigrant or nonimmigrant visa and proof of their landed immigrant status, and only if the travel both originates in Canada and is through a land border or Preclearance location.”

Read: How to apply for TN status to work in the U.S.

I’m not affected by the executive order. Does that mean it’ll be easy for me to cross the border?

Not necessarily. Border officers “can come up with any number of ways to say you’re ineligible, having absolutely nothing to do with the executive order,” says Chang. He says that under general U.S. immigration law, the onus is on the traveller to prove she doesn’t plan to immigrate or work in the U.S.

“When you talk to an officer, he doesn’t have to believe that you have immigrant intent [to deny entry]. He just has to conclude that you are unable to overcome the presumption that you have it,” Chang says. “It’s very easy for him to turn someone down.”

What tips do you have for crossing the border?

If you’re a Canadian or permanent resident with ties to one of the seven countries, “it can’t hurt to have the U.S. Customs and Border Protection FAQs in hand,” says Chang. If an officer or airline employee thinks you’re unable to cross, seeing the FAQs “will cause them to think before they continue with [an incorrect position].” And try to be calm and respectful if you encounter resistance, he says.

For Canadian permanent residents from one of the seven countries flying to the U.S., leave from an airport that offers U.S. pre-clearance in Canada. For instance, Billy Bishop Airport in Toronto does not yet have U.S. preclearance, so anyone flying from there “is being inspected when they land in the U.S.,” notes Chang. “That’s a problem, because according to the fact file, a permanent resident is not allowed to do that, which means he could be put into detention” or sent home. Private planes also often get cleared upon arrival in the U.S., so avoid those.

Getting pre-cleared here in Canada also means you’ll know whether you can enter the U.S. before boarding the plane. “It’s not like you’ll land at LAX and be deported, because you arrive in the domestic area,” he says. “Worst-case scenario, you cancel your flight. You won’t be detained or locked up in Canada.”

While Chang acknowledges that there is travel risk for permanent residents due the ambiguity of the executive order, he says you’re “probably reasonably safe if you comply with the restrictions.”

Read: Crossing the border could be harder under Trump

What should I do if I’m denied entry into the U.S.?

“Find out exactly why they’re claiming you’re ineligible,” says Chang. “At airports, they tend to do a Withdrawal of Application of Admission [Form I-275], which means you’re withdrawing your application to enter. That document will sometimes state the reason. Otherwise, you have the right to ask.”

You can also ask to speak to a more senior officer to see if they’ll reverse the decision, he says.

While a finding of immigrant intent is nearly impossible to overturn, Chang suggests consulting an immigration lawyer if the officers incorrectly claim the executive order applies. “If it’s something legally incorrect, we can fight them on that,” he says.

The consulates don’t have authority over the border, he adds, so they can’t help you.

What about non-Canadians affected by the executive order who are still in the U.S.?

“My colleagues in the U.S. are saying you’re fairly protected if you’re already in the country,” says Chang. “But if you leave, you probably aren’t going to get back in.”

Permanent residents of the U.S. are supposed to be able to enter and leave freely, he points out, “but even then there’s no absolute guarantee.” And if you’re on a temporary work permit, says Chang, “don’t leave, because you won’t get back in.”

Read: Trump to halt DoL fiduciary rule, review Dodd-Frank

If I’m affected by the order and want to leave the U.S, is that allowed?

Absolutely, says Chang. “They want you out.”