COLUMBIA--If the South Carolina Legislature passes tougher drunken driving laws this session, lawmakers may direct the state attorney general to sue the U.S. government for making them do it.

They say it's a matter of states' rights -- something that many members of the General Assembly take quite seriously.

The federal government has threatened to withhold $63 million in highway dollars from South Carolina if the state does not adopt a lower blood-alcohol content level for a person to be considered legally drunk. Last month, a measure to make that change passed the state House, but senators sent the bill back to committee Wednesday for more work.

Before the bill was sent to committee, however, the Senate added an amendment directing state Attorney General Henry McMaster to file a lawsuit challenging the constitutionality of the federal mandate.

"It's time to stop this stuff. We can't sit here and let them extort out of us what they want," Senate President Pro Tempore Glenn McConnell said Wednesday.

McConnell said the federal government does not have the constitutional authority to withhold money -- particularly money collected in the state -- because of the state's refusal to enact a law consistent with federal policy. A federal law withholds highway funds from states that do not pass a .08 blood-alcohol standard for legal intoxication.

The way the amendment is written, if the lawsuit were successful, South Carolina's DUI laws would revert to their current form.

The bill sent back to committee Wednesday would lower the state's blood-alcohol limit to .08 percent for a person to be considered legally intoxicated. Currently, the level is .10 percent.

The House-approved version of the .08 legislation also lowers the limit at which a person is considered sober. Currently, a person with a blood-alcohol content of .05 percent or less is not considered to be under the influence, while a person with a level of above .05 but below .10 can be found to be impaired if there is other evidence to support the charge. The House version would lower that to .04 percent.

McConnell, R-Charleston, argued that the House version, which he opposes, needed to be cleaned up in committee. He also authored the amendment instructing the attorney general to sue.

He said the bill, as written, undermines the jury trial system and hangs the fate of the accused on the accuracy of machines, stripping away rights. McConnell and others, including Sen. Robert Ford, D-Charleston, argued that such a law basically amounts to a witch hunt on social drinkers while doing nothing to target the repeat offenders who drive with high blood-alcohol levels.

Trey Walker, spokesman for McMaster, said Wednesday evening that the attorney general could not comment on the legislation because he had not seen it.