WASHINGTON, United States (AFP) — How much sovereignty does the island of Puerto Rico possess? The US Supreme Court on Wednesday took up that question, a crucial one for a Caribbean territory torn between its ties to the United States and its desire for greater autonomy.

The debate on that fundamental issue lately has been overshadowed by a debt crisis that has engulfed the US possession, underscoring its complicated relationship with the mainland.

On Monday, it defaulted on payments on its US$70-billion debt and its leaders have pressed the US Congress to grant it court-supervised bankruptcy protection to restructure its debt, a separate issue that the Supreme Court has agreed to hear later this year.

With the economic crisis as a backdrop, the court’s nine justices on Wednesday examined Puerto Rico’s hybrid status as a self-governing Commonwealth whose four million inhabitants are US citizens.

As is often the case with the Supreme Court, the justices were weighing a narrow legal issue that could have much broader consequences.

The case before them involves two inhabitants of Puerto Rico, Luis Sanchez Valle and James Gomez Vasquez, who were charged locally with an illegal weapons sale.

The defendants opted to plead guilty to similar charges before a federal court, which sentenced them to prison.

Their lawyers then asked Puerto Rico to drop its charges against the pair, arguing that the US Supreme Court forbids a person being judged twice for the same crime.

Puerto Rico’s Supreme Court ruled in favour of the men, affirming that the former Spanish colony is an American territory and as such not a sovereign state.

Puerto Rico’s government, however, petitioned the US Supreme Court, insisting to the contrary that its sovereignty is based on a constitution adopted by referendum in 1952.

It further contends that Puerto Rican laws derive from its constitution and are passed by a popularly elected legislature, and that the US Congress blessed that autonomy.

Dollar, baseball and Spanish

Wednesday’s oral arguments turned on what constitutes sovereignty, comparing Puerto Rico to other unincorporated US territories, like Guam, the Virgin Islands and American Samoa.

The most densely populated of these territories, Puerto Rico uses the dollar as official currency, but in many other respects has a distinct culture.

Its baseball-loving residents speak Spanish rather than English; they do not have the right to vote in US national elections; and they don’t have a vote in the US Congress.

Instead, they elect their own governor and legislature, which have autonomy over the island’s internal affairs. Defence and foreign policy remain under Washington.

Despite all that, Adam Unikowsky, the lawyer for Sanchez Valle and Gomez Vasquez, argued that the ultimate source of power in Puerto Rico is the US Congress, a position shared by the Obama administration.

“Under our constitution, states are sovereign and territories are not. Although Puerto Rico has undisputedly achieved a historic degree of autonomy, it remains a territory under Article IV (of the constitution). As such, it cannot be considered sovereign for double jeopardy purposes,” he said.

Christopher Landau, Puerto Rico’s lawyer, said that was false, insisting, “The political power of the Commonwealth emanates from the people.”

That argument seemed to strike a chord with the court’s more liberal justices, including Sonia Sotomayor, who is herself of Puerto Rican descent.

“This is a very simple question. Can the federal government override a Puerto Rican law?” she said.

Said Justice Elena Kagan: “It does seem as if Congress has given Puerto Rico as much authority as it possibly could have short of making it a state itself.”