An Oregon federal judge on Tuesday halted President TrumpDonald John TrumpTrump mocks Newsweek over story on Thanksgiving plans Obama looms over divided Democratic primary Fox News host on Warren: 'Fitting' to talk about 'Pocahontas' on Thanksgiving MORE’s effort to require people trying to enter the U.S. with certain visas to have health insurance or otherwise prove they can afford to pay for medical costs before obtaining their visa. 

U.S. District Court Judge Michael Simon, an Obama appointee, issued the order that would prevent the State Department from enforcing the policy, which was announced in October and would significantly curtail immigrants’ ability to migrate to the U.S. and obtain visas. 

Simon said in his ruling that the requirement that immigrants buy unsubsidized insurance would illegally hinder the ability of poorer immigrants from entering the country.

"The proclamation is anticipated to affect approximately 60 percent of all immigrant visa applicants," Simon wrote. "The president offers no national security or foreign relations justification for this sweeping change in immigration law."

Simon also dismissed the government’s argument that migrants would not suffer irreparable harm because their family members’ visas will only be “delayed,” noting that the proposal could prevent some immigrants from entering the country and thus separating families. 

“These are immigrant applicants for whom it has already been determined it would be an ‘extreme hardship’ on family members for them to be separated,” he wrote.

Officials could have started enforcing the policy on Dec. 1 if Simon hadn’t issued his ruling.

In a statement Wednesday, the White House indicated it would appeal. 

"Yesterday, a single district court in Oregon has decided immigration policy for the Nation. Congress plainly provided the President with broad authority to impose additional restrictions or limitations on the entry of aliens into the United States," press secretary Stephanie GrishamStephanie GrishamTrump mocks Newsweek over story on Thanksgiving plans George Conway denies that he and Kellyanne are 'Anonymous' author Trump announces restart to Taliban peace talks in surprise Afghanistan visit MORE said in a statement. 'We look forward to defending the President's lawful action."

Esther Sung, Senior Litigator at the Justice Action Center and one of the litigators, praised the ruling.

"During this Thanksgiving week, we are so grateful for this court ruling that will keep families together and allow other families to reunite. This decision is an important check on the Trump administration's effort to rewrite our nation's immigration and health care laws in violation of the boundaries set out in the Constitution,"  Sung said in a statement.

“Today's decision protects our Nation's immigrant families from suffering irreparable harm as a result of the President's harmful and unlawful proclamation. We are encouraged by the Court's decision to enforce the rule of law, which does not allow the President to rewrite our immigration laws this way,” added Nadia Dahab, Senior Staff Attorney at Innovation Law Lab, another litigator.

Simon had already issued a temporary block against the policy from being implemented earlier this month, citing concerns about the new requirements’ legality.

The policy was first proposed in an October proclamation from Trump, in which he put forth parameters for the types of health insurance that immigrants could buy in order to obtain a visa. Under the plan, immigrants would not be able to use federal subsidies to buy coverage on ObamaCare exchanges but could purchase shorter-term insurance plans promoted by the government that do not offer as expansive coverage.

The plaintiffs alleged in their suit before Simon that the policy would prevent up to 375,000 people who could otherwise legally enter the country from crossing the border.

Updated at 9:38 a.m.