A 2017 change in the law meant those suspected of crime could only be on bail without charge for a maximum of 28 days, unless there are exceptional circumstances.
Instead, suspects are now more likely to be "released under investigation".
The move was instigated in a bid to speed up cases and reduce stigma for those facing a criminal probe, after the authorities were criticised for the way celebrities such as Sir Cliff Richard and Paul Gambaccini were subject to lengthy police investigations before being cleared.
But despite that, nearly 7,000 people in West Yorkshire are currently classed as having been released under investigation. 1,169 of those have had that status for more than 12 months.
A report accompanying the figures said a sample of cases that were more than a year old had been found to be "more complex".
It added: "A large number had outstanding forensic work including digital forensics; others were with the Crown Prosecution Service (CPS) awaiting charging advice.
"Some were found lacking sufficient detail to establish why the investigation had taken so long."
But a member of West Yorkshire's Police and Crime Panel criticised the findings at a meeting on Friday.
Magistrate Roger Grasby told the region's Police and Crime Commissioner (PCC) Mark Burns-Williamson that the situation was seriously affecting the lives of suspects left in limbo.
He said: "To some extent this report is written, understandably, from a police perspective, rather than that of a libertarian in a free society.
"You'll recall that in 2015, West Yorkshire Police had the second highest number of suspects under investigation, with only The Met Police having more.
"The Panel felt at the time this was a case of kicking the can down the road, not getting on with cases, and possibly an inappropriate use of police powers.
"My concern for victims is as strong as yours, but it seems the police service don’t appreciate what being on bail means for individuals.
"You have difficultly applying for a job and it goes on your CRB."
Mr Grasby made reference to recent high-profile cases, which have resulted in the likes of Sir Cliff and BBC DJ Gambaccini calling for pre-charge anonymity for those suspected of a sex offence.
He added: "Some of those celebrities were on bail for 18 months, and were unable to get on with their lives.
Mr Burns-Williamson said he was conscious of a national debate around the law changes, but said it was too early to decide whether or not they had been positive or not.
The PCC said: "I’m aware of those high profile cases, but on the other hand there’s concerns expressed on the other side regarding the vulnerability of victims. I know there's been a lot of commentary in the media about this. It's a national issue.
"If you'll pardon the pun, the jury is still out on the effect of this and how it’s being managed.
"The report's not intended to be a full analysis of whether or not it’s working at this stage."
Local Democracy Reporting Service