What happened?

From NPR earlier today:

In a filing with the U.S. Supreme Court, the Trump administration has reaffirmed its position that the Affordable Care Act in its entirety is illegal because Congress eliminated the individual tax penalty for failing to purchase medical insurance.

Solicitor General Noel Francisco, the government's chief advocate before the Supreme Court, said in a brief that the other provisions of Obamacare are impossible to separate from the individual mandate and that "it necessarily follows that the rest of the ACA must also fall."

What would be the effect?

According to the New York Times:

If successful, the move would permanently end the health insurance program popularly known as Obamacare and wipe out coverage for as many as 23 million Americans.

And as NBC News notes, it would also affect those with pre-existing conditions:

The brief includes a section pointedly arguing that the Affordable Care Act's pre-existing condition rules must be overturned as well.

And what about WV Attorney General Patrick Morrisey?

Yes, he is part of the Republican AG group. From WV Metro News:

The attorneys general — which includes West Virginia’s Patrick Morrisey — and the Justice Department have argued the individual mandate is crucial for the law to function, and altering the provision affected multiple parts of “Obamacare.”