A Montgomery County judge on Monday struck down a petition challenging a law that curtails expansive bargaining rights for the county’s police union.

The petition challenges a law that was unanimously approved last summer by the Montgomery County Council and prevents the union, Fraternal Order of Police Lodge 35, from negotiating with county officials on day-to-day duties, such as checking e-mail.

In November, county elections officials certified about 35,000 signatures on the petition – about 4,500 more than what the police union needed. Soon after, county officials said potentially thousands of signatures were missing dates, first initials or middle names. In an unusual lawsuit, the county sued the county board of elections to block the petition.

But what caused the judge, Eric M. Johnson, to reject the petition were problems he found with the petitioners who collected the signatures. Signature gatherers are required to certify petition documents by signing their names and providing certain biographical information.

Johnson ruled that four of the petitioners had provided inaccurate information. One of the petitioners, Faye Lapp, provided the address of a vacant lot for her place of residence. The other three had not written the correct zip code of their places of residence. Because of these errors, the more than 8,000 signatures they collected needed to be invalidated.

Union officials paid petitioning firm PCI Consultants to help them with the petition. Signatures gatherers drawn from across the country descended last fall on parking lots, supermarkets and malls throughout Montgomery County. The four signature gatherers were employed by PCI.

In an interview last week, PCI president Angelo Paparella said such errors are “administrative” and “minor.” They should not interfere with “the will of the voters,” he said.

“I know that Maryland is not an initiative state per se, so there’s not as much case law, but I just can’t imagine that voters would want their signature invalidated because somebody signing the bottom of the circulator made a mistake on their address,” Paparella said. “That’s just crazy.”

Johnson is expected to file his ruling in writing within the week, after which lawyers representing the board of elections and police union may appeal. Jonathan Shurberg, a lawyer representing the county, has said he believes the case will appear before the state Court of Appeals, the highest court in the state. F.J. Collins, a lawyer representing the police union, said in an e-mail Tuesday that an appeal is under consideration.