The remedy also sent jitters through the legal departments of the most powerful financial institutions in the United States.

The Federal Reserve and the Clearing House, a trade group representing the world’s largest commercial banks, told the judge to make sure his order would not affect the funds transfer system, which automatically moves an average of $2.6 trillion a day in half a million transfers between more than 7,000 banks.

As with so many other things involving Argentina, this case is rooted in the bloody dictatorship that ruled from 1976 to 1983. The military junta more than tripled the country’s foreign debts. By 2001, the burden had become unsustainable and the economy collapsed. Argentina’s $95 billion default still stands as a world record.

Sovereign debt is supposed to be paid no matter who runs a country, but President Fernández has always considered this defaulted debt to be illegitimate, forced onto the Argentines by dictators acting in concert with international financial speculators. She and her late husband and predecessor, Néstor Kirchner, who took office in 2003, have never made any payments on the defaulted bonds.

Instead, they offered new bonds paying less than 30 cents for each dollar owed in default, and by 2010, 93 percent of the original bondholders agreed to the swaps.

Holdouts led by NML Capital, an investment fund owned by the American billionaire Paul Singer, refused the swaps, insisting on payment in full plus interest. Mr. Singer’s lawyers have traveled the world since then seeking to embargo Argentine assets, even getting its navy ship Libertad seized in Ghana as collateral. But they have never collected.

The judge’s solution to all this was to force Argentina to pay the holdouts an equal amount each time it made a payment to the exchange bondholders. And since the latter group is due to get $3.3 billion on Dec. 15, the judge said the holdouts must get their entire $1.3 billion by then as well.