Excerpt: Chief Justice John G. Roberts Jr. suggested that the government might require Americans to buy cellphones to be ready for emergencies. And Justice Antonin Scalia asked if the government might require Americans to buy broccoli or automobiles.

Reporting from Washington—By Noam N. Levey – March 27, 2012, 8:20 a.m.

The Supreme Court’s conservative justices Tuesday laid into the requirement in the Obama administration’s healthcare law that Americans have health insurance, as the court began a much-anticipated second day of arguments on the controversial legislation.

Even before the administration’s top lawyer could get three minutes into his defense of the mandate, some justices accused the government of pushing for excessive authority to require Americans to buy anything.

“Are there any limits,” asked Justice Anthony Kennedy, one of three conservative justices whose votes are seen as crucial to the fate of the unprecedented insurance mandate.

PHOTOS: Demonstrations outside Supreme Court

Chief Justice John G. Roberts Jr. suggested that the government might require Americans to buy cellphones to be ready for emergencies. And Justice Antonin Scalia asked if the government might require Americans to buy broccoli or automobiles.

“If the government can do this, what else can it … do?” Scalia asked.

The tough questioning of the administration’s lawyer is no sure sign of how the justices will rule when they hand down their decision in the case, Department of Health and Human Services, et al., vs. State of Florida, et al., likely in June.

But Tuesday’s arguments may signal…