Venezuelan President Nicolás Maduro stripped the National Assembly of central bank control this month. (Carlos Garcia Rawlins/Reuters)

VENEZUELA’S FAILING populist government has responded to the opposition’s landslide victory in a congressional election last month with a crude political coup. The government of Nicolás Maduro first used its majority in the lame-duck National Assembly to pack the constitutional court with new members. That court then moved to suspend the results of the election in one state, thereby depriving the opposition of a supermajority that would give it extraordinary powers. On Monday, the court followed up by declaring that all actions of the new National Assembly would be null and void — in effect canceling the results of the election.

Venezuela’s neighbors in the Organization of American States, including the United States, have the authority to act against this blatant rupture of the political order under the region’s democratic charter. If they fail to do so, they will bear some of the responsibility for the explosive conflict that could unfold in Venezuela in the coming weeks.

Though the government has not yet employed violence, it has trampled on the constitution in order to avoid ceding a measure of power to the opposition, which had said it would free political prisoners and take steps to stabilize the crashing economy. The new constitutional court judges were installed without procedures such as hearings, and in violation of a requirement that they be nonpartisan; one had just lost his seat in the congressional election.

The court, similarly, ordered that the election of three opposition legislators be suspended without hearing arguments, even though the victories had already been ratified by the government-controlled election commission. When the opposition leadership proceeded to swear in the new congressmen, the government’s court appointees declared that all future actions by the assembly would have no effect — a gross abuse of power.

Mr. Maduro and Diosdado Cabello, the regime’s second most powerful figure, are now suggesting they will rule without a National Assembly. Mr. Maduro already issued a decree subordinating the Central Bank to his government. He installed as his economy chief a radical leftist who has declared that “inflation does not exist in real life” — this in a country whose triple-digit rate of price increases is the highest in the world.

These tactics have prompted the divided opposition to turn toward its own hard-line leaders, even as Venezuelans struggle with mounting shortages of basic goods and soaring crime. As moderate former presidential candidate Henrique Capriles pointed out, the government is likely trying to provoke a violent confrontation.

That is something that the Obama administration and Latin America’s leaders should be working to head off. The Inter-American Democratic Charter, adopted in 2001, gives them a tool: It provides for collective action by OAS members following “an unconstitutional alteration of the constitutional regime that seriously impairs the democratic order in a member state.” The Venezuelan government’s actions clearly meet that definition.

The Obama administration should prepare its own measures. Mr. Cabello has been widely reported to be the target of a federal criminal narcotics investigation, while two of Mr. Maduro’s nephews already are imprisoned in New York on trafficking charges. Washington should make clear that Venezuela’s regime also will be held accountable for its interruption of the constitutional order, and for any use of force.