Defense lawyer Mark Geragos will try to convince the judge in the Scott Peterson double-murder case Wednesday that global positioning technology is inaccurate and unreliable.
Legal experts said he faces an uphill battle, since the technology has been in use for many years by airline pilots and even hikers to pinpoint locations to within a few feet, using signals bounced off satellites.
Geragos has said his client was tracked by Global Positioning System devices placed by authorities in vehicles he drove after his wife, Laci, disappeared on Christmas Eve in 2002. Geragos wants all the GPS tracking evidence excluded from the trial.
"The GPS technology has not been generally accepted by the scientific community," he contended in court papers filed in October.
Geragos faces a gag order and can't comment on what he hopes to gain by keeping the tracking evidence out of the trial. Likewise, prosecutors haven't said how they hope to use the evidence.
If his claims about GPS unreliability fail to persuade Judge Alfred A. Delucchi at the Wednesday hearing, Geragos hopes to prove the device used to track Peterson was operated improperly by Modesto police.
Police used GPS to track Peterson from Jan. 3 through April 22, 2003, when they arrested him near San Diego only days after the bodies of his wife and unborn son surfaced in San Francisco Bay.
GPS was first developed for military use in 1978. In California, prosecutors who use GPS evidence in court are required to establish the device's reliability using properly qualified experts.
Prosecutors not connected to the Peterson trial say this shouldn't pose a problem.
"We all know from how much we use GPS now that it's quite accurate," said Mark Hutchins, senior deputy district attorney in Alameda County. "Airplanes use it. Everyone's got a GPS map thing in their car."
On Monday, the judge presiding over Scott Peterson's double-murder trial ordered that the witness lists and names of potential jurors remain confidential, despite protests by the media.
Judge Alfred A. Delucchi, who said he hopes to begin jury selection in about two weeks, told attorneys at a pretrial hearing Monday that he had "nothing against the press. I have a responsibility here to see that Mr. Peterson gets a fair trial."
Karl Olson, who represented the San Francisco Chronicle, Los Angeles Times, The Associated Press and other media outlets, argued that "justice works best when exposed to public scrutiny."
Both prosecutors and defense attorneys disagreed.
"The media has taken great steps to place themselves in the middle of this case," said prosecutor David Harris. "The media has a right to gain information, but they don't have the right to interfere with a criminal trial."
Peterson's lawyer, Mark Geragos, said he was concerned the media would harass witnesses, citing examples of Web sites publicizing witnesses' names, addresses and phone numbers.
"The fringe elements ... have turned this into a circus," he said, adding that two new billboards near freeway entrances close to the courthouse display a photograph of Peterson with the question, "Man or Monster?"