Delving into Miami-Dade’s tricky exile politics, Florida lawmakers passed sweeping but little-noticed legislation this session prohibiting local governments from hiring companies that do business with Cuba.

The law appears to target one of the county’s largest contractors: Odebrecht USA, the Coral Gables-based subsidiary of the giant Brazilian conglomerate. The parent company’s Cuban affiliate is participating in a major expansion at the Port of Mariel.

Miami-Dade legislators, with near-unanimous support of the Florida House of Representatives and Senate, pushed the bill as a way to keep taxpayer dollars out of the hands of repressive regimes. The law also applies to companies that work in Syria, which, like Cuba, is on the U.S. list of state sponsors of terrorism.

“It puts the decision on the companies that are affected,” said Rep. Michael Bileca, a Miami Republican and one of the bill’s sponsors. “Do they want to do business in Florida, or do they want to do business in these countries?”

Yet a major portion of the legislation, which applies to contracts worth at least $1 million, seems likely to face a court challenge for interfering with the federal government’s power to set foreign policy, experts said.

Statutes limiting local governments’ contracting decisions based on the vendor’s international work oversteps a state’s power, said Dan O’Flaherty, vice president of the Washington D.C.-based National Foreign Trade Council, which advocates trade with Cuba.

“It’s unconstitutional,” he said, citing a 2000 Trade Council case in which the U.S. Supreme Court struck down a Massachusetts law restricting state businesses from dealing with companies with ties to Myanmar, formerly known as Burma.

“States are barred by the Supreme Court decision from enacting procurement sanctions targeting companies doing business in foreign country ‘X,’ ” added O’Flaherty, whose organization sent letters to Gov. Rick Scott and House and Senate leaders in opposition.

In general, state and local governments are barred from setting policy that conflicts with federal law.

A Florida House staff analysis suggested Congress has authorized the type of contractual restrictions in the legislation, which takes effect July 1 and is not retroactive. But Miami-Dade has lost past battles over Cuba policy.

In 2007, county attorneys advised that Miami-Dade couldn’t consider contractors’ Cuba ties in awarding the Port of Miami tunnel project. Activists opposed giving work to Bouygues Travaux Publics because an affiliate of the French firm built 11 resorts in ventures with the Cuban military.

And in 2000, a federal judge struck down the county’s “Cuba affidavits,” which tried to deny funding to nonprofits with ties to the island.

Bruce Rogow, who challenged that policy, predicted the new law — if it passes muster with the governor — won’t stand.

“It’s unenforceable,” said Rogow, a constitutional law professor at Nova Southeastern University. “If there is no federal law making it illegal to do business with Cuba or Syria, state law can’t make it so.”

Not so, countered Mauricio Claver-Carone, director of pro-embargo U.S.-Cuba Democracy Political Action Committee.

“This doesn’t say Odebrecht USA has to leave,” said Claver-Carone, who has criticized the firm on his blog, Capitol Hill Cubans. “They can stay and do private business in Florida. It basically does not allow for public taxpayer money to be used — that is money from many of the victims of the Cuban government.”