WASHINGTON (BLOOMBERG) - The Trump administration’s revised travel ban faced a new court challenge as soon as it took effect Thursday after the president’s signature immigration policy already weathered months of protests, legal wrangling and delays.

A new set of restrictions on refugees and immigrants from six predominantly Muslim countries took effect at 8 pm EDT (8am Friday Singapore time). The administration said the rules should help prevent the chaotic airport scenes witnessed when President Donald Trump’s initial order was abruptly imposed in January. But a half-hour before the ban took effect, Hawaii asked a judge to clarify whether the government violated instructions from the US Supreme Court in defining who’s covered by the ban and who’s excluded. The U.S. Justice Department declined to comment.

If implemented as intended, the travel restrictions would allow Trump to declare partial victory on his campaign promise to stem the flow of refugees and travellers from nations he deems a security risk. Lower court decisions to uphold two of his proposed travel bans were early, public defeats for the administration in its initial weeks.

To minimise disruptions this time, the State Department, Homeland Security Department and Justice Department coordinated in advance to establish clearer guidelines for thousands of consular officers, airlines and travellers. And unlike in January, when hundreds of travellers arriving in the U.S. were turned back or detained at airports, those already holding a valid visa will be let in.

The American public could have legitimate concerns about their safety when we open our doors,” State Department spokeswoman Heather Nauert said at a briefing on Thursday. “We want to open our doors to people who are willing to go through proper screening measures and who want to be here and want to be productive members of our society.”

The latest effort followed a US Supreme Court ruling this week that travellers from the six nations – Iran, Libya, Somalia, Sudan, Syria and Yemen – with “bona fide” connections in the US be exempted from the travel ban. That definition was interpreted to mean that travellers with specific, close family members in the US, including spouses, children, and siblings, could be let in. But people whose closest connections are grandparents, aunts and uncles could be barred. Students or travellers with business or professional ties from the affected countries also are exempt if they can show a relationship that’s formal and documented, and not based on an intent to evade the ban.

Hawaii is now taking issue with how the government defines family ties. “Our concern is that when you read their definition of what constitutes a close family relationship, they’re cutting out a lot of people,” said the state’s attorney general, Doug Chin. He filed his emergency request for clarification with the same judge, Derrick Watson, who previously blocked Trump’s March executive order from taking effect.

The Supreme Court’s decision also revived Trump’s efforts to suspend refugee admissions for 120 days and to reduce the maximum number of refugees allowed into the country to 50,000 from 110,000. The president has cited the risk of terrorists slipping into the US, while critics have said the ban discriminates against Muslims.

Speaking to reporters on background, an administration official said the US needs every available tool to keep terrorists from coming to the country. The State Department’s official guidance, which was posted on its website, grants significant discretion to consular officers who will approve visas in US embassies and outposts around the world. For example, guidance sent to embassies says that consular officers can determine whether granting a visa to an applicant from one of the six nations would be in the US’s national interest, even if they don’t have the close familial connections normally required. Yet many of the original criticisms of the ban remain.

Administration officials wouldn’t explain why the ban targets the six countries or why refugees are deemed a threat to national security. Of 784,000 refugees resettled in the US since 2011, just three were arrested for allegedly planning terrorist activities, according to the Migration Policy Institute.

Criticism was also swift toward the government’s conclusion about what constitutes a “bona fide” family relationship – for example, its refusal to consider grandparent a direct relative. Officials said they were using a definition outlined in the other parts of US law.

“We came here with a dream, you know, of what America is, and we’re just pretty disappointed by everything that is happening,” said Rama Issa, the executive director of the Arab American Association of New York. Issa, a Syrian-American, said she had postponed her wedding because many family members wouldn’t be able to join. “To us, extended family is also our nuclear family,” she said.

In a letter sent June 28 to Secretary of State Rex Tillerson and John Kelly, the secretary of homeland security, Refugee Council USA asked that the U.S. give a blanket waiver to unaccompanied children even if they don’t have a “bona fide” relationship with people or entities in the US. “This population of extraordinarily vulnerable refugee children, who have lost or been separated from their parents, often have no other options,” the group said. “As a result, they should not be left in harm’s way.”

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The government quickly backed off on at least one controversial restriction. In a version of the new rules posted earlier on Thursday, fiances weren’t among those deemed as having ”bona fide” ties. But later in the day, without explanation, the State Department updated its guidance to say that fiancés would be treated as close family members.

Air Carriers Nongovernmental organisations and refugee advocates have struggled to determine how many people will actually be affected by the new restrictions. The US has already admitted about 49,000 refugees so far this year, just shy of the executive order’s 50,000 cap. Air carriers affected by the measures said they’ll accept the presentation of official paperwork for entering the US as indicating that passengers already meet the new requirements. Dubai-based Emirates, which ranks as the world’s biggest long-haul airline and has flights from Iran and Sudan among the affected countries, said ahead of the ban’s implementation that its US services were operating as usual. “All passengers must possess the appropriate travel documents, including a valid US entry visa, in order to travel,” it said. “Emirates remains guided by the US Customs and Border Protection on this matter.”

The Department of Homeland Security said it expects a smooth implementation. “US Customs and Border Protection officers are trained and prepared to professionally process in accordance with the laws of the United States persons with valid visas who present themselves for entry,” according to a DHS statement. “We expect no disruptions to service.”

Zahra Billoo, executive director of the Council of American Islamic Relations in San Francisco, was at the city’s international airport on Thursday when the travel restrictions took effect, waiting for refugees and immigrants in need of legal aid. Standing among protesters who were rallying against the president’s decree, Billoo said she hopes Hawaii’s legal challenge succeeds.

“We’re hopeful that continued legal challenges will make it near impossible for the Trump administration to implement any portion of the Muslim or refugee ban,” she said, adding that the Supreme Court may be asked to clarify its ruling. “This is uncharted territory.”