The judge in question, Susan Bolton, found that the Arizona law's enforcement provisions were pre-empted by federal law, and thus ran afoul of the supremacy clause in the U.S. Constitution. But though her decision has enraged conservative activists, she has in the past enjoyed GOP support, and elected Republicans are being notably restrained in their criticisms.
Kyl recommended Bolton in 2000, at the end of Bill Clinton's second term, and actively supported her confirmation.
"I don't know if it's so much judicial activism as it is a failure to understand the federal government's responsibility when they don't carry out their responsibility then the states have to do it for themselves as a matter of security," said Sen. John McCain (R-AZ).
On Wednesday, Kyl and McCain issued a joint statement disagreeing with Bolton's decision, but placing the onus for predicament on the Obama administration.
Sen. Orrin Hatch (R-UT) came closer than any Republican to criticizing Bolton.
"This was a Clinton-appointed, more liberal judge," said Sen. Orrin Hatch (R-UT). "And I think the real issue is: if a state is a border state, and it is continually abused by gangs, coyotes, and people who murder their citizens, and the federal government does not do its responsibility which is to take care of the borders, then it seems highly unlikely to me that the Supreme Court of the United States will uphold that judge, prohibiting the state from doing what it has to do to protect its citizens."
"I wouldn't call it activist, but I would call it a try-to-bridge-the-gaps decision," Hatch added. "She was clearly trying to balance it."
"The idea that an officer might make mistakes seems to me to be a thin reed on which to declare a law unconstitutional," said Rep. Dan Lungren (R-CA), who once served as state Attorney General.
"I haven't had a chance to read it in its entirety so I can't tell you [if it's judicial activism]," Lungren added. "If that is the basis, as I understand the parts I was able to take a look at, it's not -- what would be the opposite of activist? It's not a non-activist judgment, I guess I'd say that."