SAN JOSE — Santa Clara County officials are poised to approve sweeping rules governing police use of cell phone trackers and other spying technology that advocates say will be a model for the nation but that cops worry could hamper investigations.

“Santa Clara County is asking and answering the right questions,” said Nicole Ozer of the ACLU’s Northern California chapter. “It’s going to be a model for moving forward for other cities and counties.”

But the sheriff’s and district attorney’s offices have both said that the ordinance could prove cumbersome because of the need to report on what’s being done in the field with surveillance technology.

“Our concern involves the tediousness of trying to log and capture daily uses among several hundred deputies in the streets,” said Assistant Sheriff Ken Binder, referring to proposed body-worn cameras for deputies falling under the auspices of the ordinance. “How do we chart that and report it at the end of the year? It makes the job more onerous in terms of doing the job and investigative work.”

County Supervisor Joe Simitian’s proposal for an electronic surveillance ordinance has been in the works since late 2014. Such privacy concerns have garnered greater scrutiny in Santa Clara County since then because of the sheriff’s plan, since suspended, to quietly acquire a cellphone tracking device commonly called a Stingray.

Similar conflicts over police spying and privacy have arisen numerous times locally and around the nation. Examples include the San Jose Police Department’s acquisition of a drone, the use and retention of information captured on license plate readers and the creation of a “Domain Awareness Center” electronic information aggregation hub in Oakland.

The proposed Santa Clara County ordinance would apply only to Santa Clara County agencies, and not prohibit the use of surveillance evidence coming from outside jurisdictions — the district attorney’s prosecution of a San Jose police case, for example, or a tip coming in from another agency regarding a fugitive whose license plate was picked up on a scanner.

State Sen. Jerry Hill, D-San Mateo, passed bills last fall that require agencies to let the public know about the acquisition of a Stingray or license plate reader.

Simitian’s ordinance, which is being finalized and expected to go before the full board sometime in May, goes much further and mandates that government agencies publicly establish a policy before any new surveillance technology is acquired or used. It also requires annual reports on how the technology is used and what the results have been. What makes it different from other ordinances around the nation is that rather than target named gadgets, the language encompasses any surveillance-related technology, including what can’t be foreseen. Simitian has called it “future-proof.”

In Seattle, for example, regulations were tied to “a finite set of technologies” and the laws “were obsolete as soon as they were passed,” wrote ACLU attorney Matt Cagle in an April 13 letter to the county’s Finance and Government Operations Committee, which heard the matter on Thursday and forwarded it to the Board of Supervisors with a recommendation for approval.

“Santa Clara is the farthest along, and it’s certainly an issue many Californians want to see at a local level,” Ozer said.. She pointed to recent revelations that San Jose and Oakland police have been quietly using a social media monitoring tool as an example of why rules need to be flexible.

Ozer cited a Tulchin Research poll that found 67 percent of 800 voters surveyed wanted to see local-level government approve police surveillance methods before they are used.

The Santa Clara County model also makes it a misdemeanor to intentionally abuse such technology — something advocates say is important because, otherwise, any violations would be handled internally at an administrative level to questionable effect.

Supervisor Cindy Chavez, who co-chairs the committee that reviewed the proposed ordinance, was sympathetic to law enforcement concerns. But Simitian said the reports would be quantitative in nature, not case-specific.

“I’m surprised this concern lingers,” he said. “I was very direct, very clear — there’s not an expectation in this ordinance that we’d get an item-by-item list of interactions any more than we would say that we want frame-by-frame review of everything that’s captured on a closed-circuit television camera.”

The Electronic Frontier Foundation, a San Francisco-based group that advocates on tech privacy issues, called finding the balance between being too specific and too broad a “tough nut to crack.”

“We particularly praise the proposal’s recognition of a pattern and practice among law enforcement departments to seek forgiveness rather than permission,” wrote Shahid Buttar of the foundation in a February letter to the committee.

Brian Hofer, who worked with an ad hoc committee in Oakland to regulate a proposed information collection hub that caused a stir in that city, agreed that the county is on the right track.

“It’s an approach that we think all local governments should follow, and it brings stuff that’s in the shadows out into the public arena,” he said. “That’s what we learned in Oakland, they went ahead and purchased things and never asked the public if they wanted it, if it was appropriate, what it meant for privacy or how it would be used. It’s genius to have that conversation in the beginning, not after we find out about something that’s been used for five years.”

Contact Eric Kurhi at 408-920-5852. Follow him at Twitter.com/erickurhi.