U.S. District Judge Derrick Watson reportedly received death threats after issuing a nationwide halt on the ban in mid-March.
The ruling sets the case up for another hearing in the San Francisco-based Ninth Circuit Court of Appeals, which upheld a block on Trump's original January 27 travel ban. Watson said in his ruling that claims of religious discrimination in the order would have a "strong likelihood of success".
President Donald Trump called Watson's ruling an example of "unprecedented judicial overreach" and said his administration would appeal it.
Federal Bureau of Investigation officials told Hawaii News Now that authorities are aware of the threats but declined to provide details on their nature or form. The US Marshals Services has since sent around a dozen deputies to provide Watson with continuous protection.
The new ban was supposed to take care of some of the legal problems, as it specifically didn't apply to green card and visa holders.
The ban would keep people from Iran, Libya, Somalia, Sudan, Syria, and Yemen from entering the USA for 90 days and all refugees for 120 days.
"While we do not discuss our specific security measures, we continuously review the security measures in place for all federal judges and take appropriate steps to provide additional protection when it is warranted".
The Maryland ruling and a separate ruling in Hawaii were victories for civil liberties groups and advocates for immigrants and refugees, who argued that Trump's temporary ban on travel from six predominantly Muslim countries violated the Constitution. The judge also blocked the suspension of the nation's refugee program.
Watson is not the only judge who blocked the ban.