Matthew Ellis, Staffordshire's Police and Crime Commissioner, put pressure on mental health service providers to agree a protocol to ensure alternatives to custody are in place.
In Staffordshire and Stoke, this partnership approach has seen the number of people detained in police custody fall by 59 per cent - from 168 in 2012 to 69 in 2014.
A report that came out yesterday by Her Majesty's Inspectorate of Constabulary (HMIC) found that police custody is too often the default response for vulnerable people in crisis.
Mr Ellis said: "Police custody is fundamentally the wrong place for an individual who is in mental health crisis to be kept if they haven't committed a crime.
"We need to stop criminalising people who are simply ill and ensure officers are not tied up with issues they are unqualified to deal with.
"The ambition for cross-agency working has really taken hold in in Staffordshire and Stoke-on-Trent, which has led to a drop of almost two-thirds in mental health detentions in custody.
"A community triage system, which I initially funded, where mental health professionals work with police officers has proved effective and will now be funded by the NHS going forward."
He added: "However, there is still work to be done. In recent weeks there have again been Section 136 detentions in police custody in the north of Staffordshire because there was not an NHS bed available.
"This is simply not acceptable and I am putting pressure on the NHS to address this as a matter of urgency."