WASHINGTON — As the Supreme Court heard arguments Wednesday about an Arizona immigration law, supporters of the crackdown set up an amp on the sidewalk in front of the court and belted out a tune:

“We’ve got illegals in the back yard

It’s time we claimed our borders once again

I think Arizona’s great

Protecting citizens of that state

And I believe that all across this land

With Arizona we should take a stand.”

The melody was weak and the lyrics weaker. But the protest anthem was noteworthy in one respect: In tone and substance, it was nearly identical to the argument Justice Antonin Scalia made inside the court.

While other justices at least attempted a veneer of fair and impartial questioning in the highly charged case, Scalia left no doubt from the start that he was a champion of the Arizona crackdown and that he would verbally lacerate anybody who felt otherwise.

“The state has no power to close its borders to people who have no right to be there?” he asked incredulously.

And: “What does ‘sovereignty’ mean if it does not include the ability to defend your borders?”

And: “Are you objecting to harassing the people who have no business being here? Surely you’re not concerned about harassing them.”

And: “We have to enforce our laws in a manner that will please Mexico?”

Technically, Scalia was questioning counsel, but at best the queries were rhetorical. At times he verged on outright heckling. He interrupted Solicitor General Donald Verrilli, who was arguing against the Arizona law, to say that his position “sounds like racial profiling to me.”

He wasn’t the wordiest justice — Sonia Sotomayor interjected 36 times to Scalia’s 35 during the 90-minute session — but he was by far the most caustic and the least inclined to subdue his partisan instincts.

During the immigration argument Wednesday, several justices were scrupulous about challenging both sides. Roberts noted that parts of the Arizona statute impose “significantly greater sanctions” than federal law does. Sotomayor informed Verrilli at one point that she was “terribly confused by your answer” and let him know that “it’s not selling very well.”

Scalia wasn’t the only ill-tempered justice in the chamber. Samuel Alito rolled his eyes to the ceiling and shook his head in objection when two liberal justices spoke. And Sotomayor took a shot at the conservative justices when she referred to “those of us for whom legislative history has some importance.”

But Scalia was the leading dyspeptic, interjecting his way through the argument. He interrupted Sotomayor, demanding to know whether Arizona “has to accept within its borders all people who have no right to be there.”

He interrupted Paul Clement, the lawyer representing Arizona, if only to mock the federal immigration authorities’ response as “yes, he’s an illegal immigrant, but that’s OK with us.”

He interrupted the solicitor general to inform him that “Arizona is not trying to kick out anybody that the federal government has not already said do not belong here” and again to say that the executive branch “doesn’t want this law enforced so rigorously.”

Scalia derisively likened the Obama administration’s position to saying that it would prosecute only “professional bank robbers” and would object when a state decides to prosecute an “amateur bank robber.”

Patiently, Verrilli explained that the Arizona law is forcing federal authorities to take their emphasis away from the most dangerous illegal immigrants, that it is merely shifting the problem to other states, and that mass incarceration risks upsetting foreign relations.

“Well, can’t you avoid that particular foreign-relations problem by simply deporting these people?” Scalia retorted. “Look, free them from the jails and send them back to the countries that are objecting. What’s the problem with that?”

The demonstrators on the sidewalk outside — with their tea party signs proclaiming “We Are a Nation of USA Citizens” and their lyrics demanding “What part of the word ‘illegal’ don’t they understand?” — made precisely the same point.