(CNN) In their first hours in control of the House of Representatives, Democrats filed a motion to intervene in an ongoing lawsuit that threatens to bring down the Affordable Care Act.

The petition is signed by new House counsel Douglas Letter who wrote, "The House seeks to offer a defense addressing the same questions of law that the present parties are litigating."

Notably, Donald Verrilli, who defended the law as former President Barack Obama's solicitor general and is now in private practice, is also on the brief representing the House.

A federal judge in Texas last month ruled that the ACA is unconstitutional because Congress eliminated the individual mandate penalty by reducing it to $0, starting this year. This rendered the mandate itself unconstitutional and the rest of the law therefore cannot stand.

The Trump administration is not defending Obamacare, so a coalition of Democratic states is appealing the judge's ruling.

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