06/08/2015 06:11 EDT | Updated 06/08/2016 05:59 EDT

His health act under threat, Obama lectures Supreme Court on constitutional law

WASHINGTON - With his proudest achievement in danger of being torpedoed by an imminent U.S. Supreme Court decision, President Barack Obama has pre-emptively fired off a rocket of his own — one aimed directly at the high court itself.

The president is challenging the court's decision to even hear a case that could shred the Affordable Care Act, the landmark legislation better known as Obamacare.

With a ruling expected this month, the president offered clear signs Monday that he's gearing up for one more possible fight over the bill that will define his legislative legacy.

The White House said Obama will deliver a speech Tuesday on the history of health reform in the United States, and a century of failed previous attempts to provide universal coverage.

He also challenged the court's wisdom in hearing the King vs. Burwell case. A group of Obamacare opponents have found a four-word phrase in the law that they believe essentially renders it invalid in 34 states.

The law's defenders call those words an insignificant error in the law's drafting.

The president switched into his role as a former constitutional law professor Monday to lecture those obsessing over what his side describes as a legislative typo.

"This should be an easy case," Obama told a news conference in Germany, before coming home from the G7 summit.

"Frankly, it probably shouldn't even have been taken up. And, you know, since we're going to get a ruling pretty quick, I think it's important for us to go ahead and assume that the Supreme Court is going to do what most legal scholars who've looked at this would expect them to do."

Under well-established legal precedent, he said, both liberal and conservative judges have historically tended to interpret laws, to the greatest extent possible, on how lawmakers intended to write them — not on the literal wording.

And he said it's clear what lawmakers intended to create in 2010: a national system of health exchanges, with some run by participating states and the rest co-ordinated by the federal government, all aimed at providing coverage across the country for people with all medical conditions.

The federal role is at the heart of the case.

The system would collapse financially in many states without being fortified by different contributions from Washington: the carrot of federal subsidies, and the stick of tax penalties from the IRS for younger, healthier people who don't buy into insurance plans.

The feds also co-ordinate insurance programs for two-third of the country — 34 states that refused to set up their own.

But according to a now-contentious turn of phrase in the law, the 2010 Affordable Care Act specifies that subsidies are available only for plans "established by the State."

Opponents of the law noticed that wording, jumped on it, and rode it all the way to the Supreme Court.

They're now hoping to succeed where Obamacare opponents narrowly failed in 2012, when they nearly convinced a majority of the justices to strike down the law but were felled by a surprise interpretation from Chief Justice John Roberts, who stunned fellow conservatives by defending the law as a tax.

Court-watchers have noted pointed questions from the bench during hearings in the current case, and suggested the law could collapse without Roberts riding to its rescue again.

Obama said the judges just need to listen to the lawmakers who voted for the bill five years ago — he said everyone agreed at the time, fans and foes alike, that the law meant federal support in every state.

He warned of the potential havoc in the insurance marketplace, should judges side against Obamacare.

"It's a bad idea. It's not something that should be done based on a twisted interpretation of four words, in, as we were reminded repeatedly, a couple-thousand-page piece of legislation."