The Department of Justice late Thursday asked the Supreme Court to reinstate President Donald Trump's travel ban on people from six Muslim-majority countries.
The department filed two emergency applications with the court seeking to overturn lower court rulings that blocked the ban on the grounds of discrimination.
In a statement, spokeswoman Sarah Isgur Flores said the government was "confident that President Trump's executive order is well within his lawful authority to keep the nation safe and protect our communities from terrorism.
"The president is not required to admit people from countries that sponsor or shelter terrorism, until he determines that they can be properly vetted and do not pose a security risk to the United States."
In January, Trump signed an executive order blocking the entry of people from Iraq, Somalia, Iran, Syria, Sudan, Libya and Yemen. However, this was defeated by legal challenges in the states of Washington and Minnesota.
An altered order -- dropping Iraq and proposing a 90-day suspension of visas for people from the other six countries, as well as a 120-day hiatus on the admission of refugees -- was blocked by a court in Maryland.
A federal judge in Hawaii also sided with the ban's opponents.
On May 25, a federal appeals court in Virginia refused to lift the temporary block, saying the Trump's order "drips with religious intolerance, animus and discrimination".
The American Civil Liberties Union said on Twitter: "We've beat this hateful ban and are ready to do it again."
The Supreme Court filled a 14-month vacancy in April when Neil Gorsuch was confirmed by the Senate.
The U.S.'s highest court now has five conservative and four liberal judges on its bench but its decisions are unlikely to be split along party lines in a complex case that involves debate around the powers of the executive branch and the freedom of religion.
