ATHENS, Ohio — An Athens County drunken-driving case could provide defense attorneys with ammunition to challenge the reliability of an alcohol breath-tester commonly used in Ohio.

Municipal Judge William A. Grim agreed to hear testimony challenging the Intoxilyzer 8000 at a hearing yesterday to determine whether the testimony will be allowed in the trial. Typically, such challenges are dismissed, citing a 1984 Ohio Supreme Court ruling that a defendant’s right to a fair trial is not harmed by not permitting expert witnesses to attack the reliability of such machines in general.

In a ruling Wednesday that allowed the testimony, however, Grim wrote that while the 1984 case is often cited to support the claim that breath-testing machines cannot be challenged in court once they’re approved by the Ohio Department of Health, he thinks judges have the authority to determine whether that evidence is allowable.

Defense attorneys — including D. Timothy Huey, president-elect of the Ohio Association of Criminal Defense Lawyers — said yesterday’s hearing was a first step toward having the Ohio Supreme Court revisit the issue.

Thomas E. Workman Jr., a Massachusetts attorney who holds a master’s degree in electrical engineering and has worked for companies including Texas Instruments, Hewlett-Packard and Xerox, testified that the machine’s design makes it more likely than others to misidentify other substances as being alcohol.Unlike older machines, the Intoxilyzer 8000 easily can be carried in the trunk of a police car and used in the field. That means suspected drunken drivers can be tested on the spot by blowing into a tube, as opposed to a time-consuming journey to and from a police station to take a test on a machine that isn’t portable.

Defense lawyers say the Intoxilyzer 8000 is less reliable than fixed instruments because of environmental factors such as heat and humidity. They note that the machine sometimes gives “ambient failures,” meaning that the presence of alcohol in the air skews the results.

Robert Jennings, a spokesman for the Ohio Department of Health, which certifies the Intoxilyzer 8000 breath-tester, said the agency remains “pretty confident about its reliability.” The portable testing machine is used by police agencies in 77 Ohio counties.

The lead defendant in the Athens County case is Nicole R. Gerome, a 29-year-old Athens woman charged with DUI after being stopped by the State Highway Patrol on March 16. Three other defendants also are seeking to allow testimony challenging the machine’s reliability in their cases.

Among the issues raised yesterday was the allegation that data from sobriety tests done with the machine, and uploaded to the Health Department’s website, are being altered or removed.

Mary Martin, the agency’s program administrator for drug and alcohol testing, testified that she “would be amazed” to learn that such changes or deletions had occurred.

Columbus lawyer Cleve Johnson, however, testified that he has downloaded multiple results for the same sobriety test. In one case, Johnson said, he found two blood-alcohol levels for a woman in Pickaway County — zero and 0.191. Now, he said, “you can no longer find the zero test, but the 0.191 test is still on there.”

Columbus lawyer Jon J. Saia said a certification test on a machine later used in Athens County returned an impossibly high alcohol level, but the machine was certified anyway. Now, Saia said, the record of the test can no longer be found on the website.

Athens City Prosecutor Lisa Eliason complained at the outset of the hearing that she thinks Grim has his heart set on getting the Supreme Court to look anew at the breath-tester issue.

“It seems that the court has clearly made up its mind, that we need a case to kick (the 1984 ruling) up to the Supreme Court,” she said.

Grim responded, “The only decision the court has made so far is that we’re going to have a hearing. … The court will follow the law.”

The hearing is scheduled to resume in late June.