In the ruling, Judge O'Connor begins by stating that courts are not "tasked with, nor are they suited to, policymaking".
Five of the current justices on the Supreme Court, including Chief Justice John Roberts, have twice declined to strike down the law.
U.S. District Judge Reed O'Connor, who ruled the Affordable Care Act "invalid" Friday, is no stranger to the conservative resistance to Obama administration policies.
The DOJ did not defend the mandate or provisions requiring guaranteed issue and community rating of policies (without regard to pre-existing health conditions, for example), which it argued were not severable and should fall with the mandate.
HealthCare.gov, the government's site for signing up, was taking applications Saturday, the deadline in most states for enrolling for coverage next year, and those benefits will take effect as scheduled January 1.
The case is expected to continue to wind through the court system, with the 16 Democratic state attorneys general who intervened in the case saying they will appeal the ruling.
Didn't the Supreme Court already uphold Obamacare in 2012? . However, a different majority held the mandate amounted to a constitutional tax penalty.
Facebook bug potentially exposed photos of 6.8 million users to developers
The problem comes in a year fraught with privacy scandals and other problems for the world's biggest social network. The apps also had access to photos posted in Facebook Stories and in the Facebook Marketplace.
Because the mandate penalty was zeroed-out, it no longer would generate revenue and can not be deemed an exercise of congressional tax power, he said. Without the federal tax credits, insurance would become unaffordable for many Americans and being a woman could once again be considered a pre-existing condition.
"And the reason you know it's a silly ruling is we haven't had a mandate with any enforceability since we passed the tax law because there's no penalty anymore and much of the law is going forward". He concluded it is "impermissible under the Interstate Commerce Clause-meaning the Individual Mandate is unconstitutional". That latter group will also include many Republicans who campaigned on the promise to protect people with pre-existing conditions and could face political consequences if they renege on that. All insurance plans are still required to provide a basic standard of benefits without lifetime caps as the law states. That process is expected to take several months. But it will need to survive review by higher courts to have any effect on the program that's credited with expanding health insurance to about 19 million people in the U.S.
The administration has slashed marketing efforts and enrollment assistance and encouraged people to buy skimpier, less expensive plans that do not meet the standards of the law.
California and other states defending the Affordable Care Act on Monday asked the federal judge who struck down the law last week to issue a new order making clear that the landmark health care reform remains in effect while appeals play out. It's unclear what form that would take, or if the Republican-majority Senate would go along and Trump would sign it.
Since its inception, Republicans have repeatedly tried and failed to repeal it.
The HealthCare.gov website is photographed in Washington, Wednesday, Oct. 31, 2018.
"A confirming Supreme Court Decision will lead to GREAT HealthCare results for Americans", Trump tweeted Monday.
But if the latest legal challenge to ObamaCare ends up before the Supreme Court, the outcome is far from certain.
"This outrageous ruling threatens health coverage for millions of Americans". But other Republicans were far more reserved, faced with the problematic prospect of a renewed Obamacare fight after the midterm election drubbing their party just took from voters anxious about health-care costs and protections for Americans with pre-existing conditions. "If this Texas decision on the ACA is upheld, it would throw the individual insurance market and the whole health care system into complete chaos", Leavitt posted on Twitter. Meanwhile, America's health care industry has expressed trepidation about what's likely to be a very uncertain road ahead.