The uncle of a Norwich woman who was brutally murdered by a violent serial abuser said more needs to be done to help victims know about potential attackers.
Clare's Law, introduced in 2014, gives people the "right to ask" their force about any previous domestic violence or offences that mean their partners could pose a risk to them.
Home Office guidance states police will aim to complete the inquiries within 35 days.
Data released under Freedom of Information laws show that response times to 375 out of 1,609 "right to ask" requests approved by police in this country in 2020 fell below this target.
Norfolk Police, one of 14 forces able to provide full statistics for the last year, was found to have disclosed 178 out of 291 requests it received (61pc) within the timescale.
A Norfolk Police spokesman insists the force ranked amongst the highest for the proportion of 'right to ask' requests which end up being disclosed.
Steve Roberts, the uncle of Kerri McAuley, 32, who was murdered in her Norwich home by Joe Storey in January 2017, said Norfolk was going in the "right direction".
The 54-year-old said: "It's pleasing to see Norfolk Police are heading in the right direction with 61pc of all requests under Clare's Law being met within the recommended time scales.
"However with a 39pc shortfall, more needs to be done to meet the excellent standards shown by the Met, Derbyshire and Staffordshire."
But he said this was only part of the picture and agencies also had a responsibility to share information.
He said: "Kerri's murderer was well known for his violent attacks on women to many agencies tasked with public protection.
"He was risk assessed at a very young age by the Probation Service as highly likely to have the propensity to carry out a fatal attack and sadly several women went on to be seriously assaulted by him, without this critical information being shared with them."
Giles Orpen-Smellie, who has been elected as Norfolk’s next police and crime commissioner said he had not yet started so could not comment on the disclosure figures.
But the new PCC, who officially starts on Thursday (May 13), said domestic abuse would "absolutely" be a key part of his agenda.
He said: "I’m mindful that domestic abuse makes up 26pc of all recorded crime in Norfolk at the moment so it’s a huge problem.
“Domestic abuse will be in my police and crime plan and will feature high up.”
A Norfolk Police spokesman said: "We consider the specific crime allegations as important when it comes to disclosure, for example stalking and coercive and controlling behaviours, which can be more difficult to convict on but where we have had some subjects with obvious patterns of behaviour, disclosure has been made despite there being no conviction (some other forces only disclose on convictions).
"We also have a lot of return applications where survivors have received previous disclosure and ask for one for their next partner or they are told to by their social worker.”
A separate FOI to Suffolk Constabulary revealed the force responded to 70 of 117 right to ask disclosure applications in 2018.
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