States are trying to toughen penalties for suspected drunken drivers who refuse to take a breath test, arguing motorists too often get a milder penalty than if they had provided evidence that could convict them.

Bills to lengthen license suspensions or make it a criminal offense to refuse a test are pending in five states, including Ohio, Massachusetts and Rhode Island, where the percentages of people refusing are among the highest in the nation.

Nationwide, an average of 25 percent of people pulled over on suspicion of drunken driving refuse to take a breath test, which is designed to estimate the amount of alcohol in the blood, according to the National Highway Traffic Safety Administration.

In every state but Nevada, the punishment is a suspended driver's license. Still, people who refuse believing they would fail a test might avoid a drunken driving conviction and jail time.

"We are seeing cases where people are being stopped 10, 15, 20, 30 times," said Massachusetts Rep. Todd Smola. "Every single case they are refusing the breath test, paying their lawyer a few bucks."

Defense attorneys and motorist groups oppose stricter penalties, and some lawmakers don't see the need.

A proposal in Illinois would increase suspensions to one year from six months. Most drunken driving cases are handled within that six months, said Rep. Robert Molaro, a Democrat from Chicago. A convicted driver would then get a more severe penalty: a revoked license. An acquitted motorist would still be punished by the suspension, which would be unfair, he said.

"What do we gain by going to a year? I don't get it," Molaro said.

In all, bills were introduced in 15 states in 2005. Some didn't make it to the debate stage. Maryland, Montana and Virginia approved stricter punishment, with Montana adding up to a $2,000 fine and two days to six months in jail if a person is caught driving with a license that was suspended for refusing a test, according to the National Conference of State Legislatures.

In Ohio, a Senate-passed proposal to double the length of most license suspensions now goes to the House. About 40 percent of Ohio suspects refuse the test, the sixth highest among 41 states where data was available, according to a study by the NHTSA. That's despite the state being among 19 that already adds penalties such as jail time to the license suspension.

Motorists refuse tests for many reasons. Maybe they have been drinking and fear failing. Some have heard stories that the machines record some diabetes symptoms as drunkenness. Those with previous drunken driving convictions might be trying to avoid a felony conviction from another arrest.

"The major problem is not with the first-time people," said Martin Aubry, municipal prosecutor in Perrysburg in northwest Ohio. "The more convictions you've had, or the more times you've been stopped, you might learn from your previous experience not to take the breath test."

Defense attorneys and motorist groups say it's unfair to force someone to face a criminal conviction for a test that might be inaccurate.

The machines are supposed to exclude results measuring artificially high alcohol levels if the person vomits or burps, increasing the amount of alcohol in the mouth. That alcohol hasn't yet reached the blood, and thus the brain.

Attorneys question the overall reliability of the machines. They say a direct blood test is the fairest and most accurate test.

"It's not what protects the presumption of innocence and what supports the burden of proof," said Brad Koffel, a Columbus defense attorney.

Prosecutors and law enforcement officers said they routinely test and calibrate their machines, and watch suspects closely for 20 minutes before testing to ensure no alcohol is brought up to the mouth.

The states with the lowest refusal rates have among the toughest penalties, with jail time in California and Nebraska and revoked vehicle registrations in Hawaii and Maine.