A US judge in Seattle has issued a temporary nationwide block on President Donald Trump's ban on travellers from seven mainly Muslim nations.
Federal Judge James Robart ruled against government lawyers' claims that US states did not have the standing to challenge Mr Trump's executive order.
Last week's order has led to protests and confusion at US airports.
Customs officials have told US airlines that they can resume boarding banned travellers while a legal case is heard.
Gulf carrier Qatar Airways told Reuters news agency it would start accepting all passengers with valid travel documents.
The administration, however, could again block them if it were to win an emergency stay. The justice department says it will appeal against the Seattle ruling.
In a statement, the White House described Mr Trump's directive as "lawful and appropriate".
"The president's order is intended to protect the homeland and he has the constitutional authority and responsibility to protect the American people," the statement said.
Mr Trump's order suspended the US Refugee Admissions Programme for 120 days.
There is also an indefinite ban on Syrian refugees. Anyone arriving from Iraq, Syria, Iran, Libya, Somalia, Sudan or Yemen faces a 90-day visa suspension.