INDIANAPOLIS -- Indiana lawmakers reopened the debate over illegal immigration Tuesday, even after experts testified that the state didn't have much ground to stand on.

Tuesday's hearing was expected to be heated, after the issue of a state immigration law was left unresolved last session, 6News' Norman Cox reported.

Most of the witnesses called on Tuesday were lawyers, many of whom questioned the state's ability to even pass an immigration law, since they argued that it is a federal responsibility.

"You can possibly push the limits of your authority under constitutional law and hope for the best," said Indiana University law professor John Scanlan.

There are cases proceeding through the federal court system that could give states more authority over immigration, but lawyers warned that until the U.S. Supreme Court rules on them, Indiana could get in trouble by proceeding on its own.

"It is not permissible, not is it prudent, for a state to take federal law into its hands. That's essentially what pre-emption is all about. It's not allowed, and if you do it, you're going to get burned at the very basic level of the pocketbook," said Valparaiso law professor Bernard Trujillo.

The committee also heard from a group that did a demographic study of Indiana, estimating that there are about 100,000 illegal immigrants in Indiana.

The committee will have four more hearings on the matter.