The Supreme Court begins its constitutional review of the health-care overhaul law Monday with a fundamental question: Is the court barred from making such a decision at this time?

The justices will hear 90 minutes of argument about whether an obscure 19th-century law — the Anti-Injunction Act — means that the court cannot pass judgment on the law until its key provisions go into effect in 2014.

It is the rare issue on which both sides agree: the Obama administration lawyers and those representing the states and private organization challenging the new law argue that the Supreme Court should decide the constitutional question now.

But a panel of the U.S. Court of Appeals for the 4th Circuit disagreed, and so the Supreme Court ordered arguments on the issue.

At the heart of the Patient Protection and Affordable Care Act is the requirement that almost all Americans either obtain health insurance by 2014 or pay a penalty. The question the court will consider Monday is whether that penalty should be considered a tax. And if it is, does the Anti-Injunction Act mean that courts must stay out of the way until someone is actually required to pay it?

The first time that could occur is when someone files a tax return in 2015, because that is how the penalty would be collected.

Since all parties in the lawsuits want the court to act now on the constitutional question, the justices appointed a private lawyer — Supreme Court practitioner Robert A. Long of the Washington law firm Covington & Burling — to present the argument that the Anti-Injunction Act says courts must wait.

The law first passed in 1867 says that “no suit for the purpose of restraining the assessment or collection of any tax shall be maintained in any court by any person.” It was designed to make sure the flow of tax collection necessary to keep the government running was not disrupted by lawsuits.

In his brief, Long points out that the penalty certainly looks like a tax — it is estimated to raise up to $6 billion a year by the end of the decade. The penalty is calculated based on a person’s income and is collected by the Internal Revenue Service.

He also noted that Congress could have provided a mechanism that allowed courts the authority to immediately decide the constitutionality of the law, but did not.

In the early stages of litigation over the health-care law, the Obama administration agreed that Anti-Injunction Act barred an immediate constitutional decision. But it dropped that argument, and told the Supreme Court that the “penalty” for failure to secure health insurance is not a “tax” for Anti-Injunction Act purposes.

The 26 states challenging the health-care law, as well as the private organization and individuals who are party to the challenge, also want the court to act now.

The “purpose” of the challenge is to “invalidate the ACA’s mandate that [individuals] purchase costly insurance,” not to block the penalty, wrote Michael A. Carvin, who is representing the organization, the National Federation of Independent Businesses, and private individuals.

Besides the 4th Circuit panel, the view that the Anti-Injunction Act forecloses a ruling at this time was endorsed by Circuit Judge Brett M. Kavanaugh, an influential conservative member of the U.S. Court of Appeals for the D.C. Circuit.

“Waiting to decide might mean never having to decide,” Kava­naugh wrote, keeping the courts out of the political fray. If there is no change in the law between now and 2015, he said, the constitutional decision could be made then.