President Obama’s executive amnesty represents a “threat” to America’s very system of government, according to House Speaker Paul Ryan.

“The Constitution is clear: Presidents don’t write laws, Congress does,” Ryan said Monday ahead of oral arguments before the Supreme Court in United States v. Texas. “Presidents may disagree with the laws, but they are not free to ignore those laws and have unelected bureaucrats write new ones.”

“This is a threat to self-government itself,” Ryan added.

Texas and 25 states have challenged Obama’s November 2014 unilateral extension of pseudo-legal status and work permits to millions of illegal immigrants. To date, the states have been successful in blocking the programs in lower courts.

The Obama administration appealed to the Supreme Court last year. The high court agreed to hear the case in January.

Last month the Republican-House adopted a resolution authorizing Ryan to file a brief with the Supreme Court stressing that Congress alone is allowed to make the laws.

“The Executive may disagree with the laws Congress enacts and may try to persuade Congress to change them. But neither any immigration law now on the books nor the Constitution empowers the Executive to authorize—let alone facilitate—the prospective violation of those laws on a massive class-wide scale,” the brief reads in part.

The Court has allotted the House 15 minutes of time in oral arguments before the court Monday. Erin Murphy, a partner at Bancroft, working pro bono for the House, will be presenting their arguments before the court.

“We have sworn an oath to defend the Constitution, and today at the Supreme Court, we will do just that,” Ryan added.