Kennedy, who nearly certainly holds the crucial vote, said it would help to know how many abortions could be performed in clinics if the law were allowed to become fully effective, and mused that it might be useful to return the case to the lower courts to develop more evidence.

"It's work. But maybe the district court should have done the work", Alito said.

All eyes were on Justice Kennedy, who seemed careful not to tip his hand. "If that's all right for the women of the El Paso area, why isn't it right for the rest of the women in Texas?". "This may not be medically wise", said Kennedy.

Kennedy asked one question that hinted he may lean in favor of the challengers. On Wednesday, he said Texas would experience a "capacity problem" if more clinics close, USA Today reported.

During an hourlong argument over what could be the court's most important abortion case in a generation, the eight justices sounded closely split and debated with each other whether Texas had gone too far in setting stringent new regulations for doctors and clinics that perform abortions.

The Texas law requires abortion doctors to have "admitting privileges" at a hospital within 30 miles (48 km) of the clinic so they can treat patients needing surgery or other critical care.

One speaker argued that anti-choice supporters were using "under handed schemes to take women's rights away." . The clinics say no more than about 10 facilities will remain open, where there once were more than 40 before the law was enacted in 2013. The best pro-lifers can hope for is a 4-4 split, which would uphold a lower court's ruling in favor of the law.

On Wednesday, it was the court's four liberals who dominated the questioning.

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Be proactive - Use the "Flag as Inappropriate" link at the upper right corner of each comment to let us know of abusive posts. Australian Transport Minister Darren Chester said the debris was approximately one metre (three feet) long.

Justice Ruth Bader Ginsburg said, "The focus must be on the ones who are burdened..."

The Georgia Life Alliance, an anti-abortion group, said it's awaiting the high court ruling to see if it can promote more clinic requirements, like the ones Texas imposed, in Georgia. While he was one of the authors of a 1992 decision saying abortion restrictions couldn't place an "undue burden" on women seeking the procedure, he spent much of yesterday's argument, as NPR's Nina Totenberg put it, "looking for a way out".

The US Supreme Court heard arguments Wednesday over a Texas law placing tough new restrictions on abortion providers that would potentially shut down all but nine or 10 clinics across the entire state. If Kennedy sides with the state of Texas, that will presumably leave the high court deadlocked 4-4.

In his earlier writings on abortion, Justice Kennedy has demonstrated a cautious support for abortion rights but a vehement opposition to late-term abortion.

But Justice Elena Kagan said the facts of what has happened as the case has worked its way through the legal process answered the questions. Meanwhile, Justice Samuel Alito said, "As to some of them, there's information that [abortion clinics] closed for reasons that had nothing to do with this law". Most of those laws are in effect.

Only Justice Clarence Thomas did not ask any questions.

A few minutes later, Roberts thanked Toti again and turned to U.S. Solicitor General Donald Verrilli, the Obama administration's top courtroom lawyer.