Complaints about police have reached record levels, figures show.
There were 37,105 complaints from members of the public against forces in England and Wales in 2014/15.
The number was an increase of 6% on the previous year, a jump of 62% over a decade and the highest since the Independent Police Complaints Commission (IPCC) started gathering the data in 2004/05.
IPCC chair Dame Anne Owers said the rise in the volume cases could be because people are "readier and more willing" to complain as well as having "more things to complain about".
Complaints can involve multiple allegations and nearly 70,000 claims were attached to the cases logged by forces.
One in seven of the allegations (14%) involved incivility, impoliteness and intolerance, 8% were classified as "other assault", 6% were categorised as oppressive conduct or harassment and 5% were linked to claims of a lack of fairness and impartiality.
There were also 150 claims of sexual assault - less than 1% of the total - while 405 were classed as "serious non-sexual assault". The most commonly recorded allegation category was "other neglect or failure in duty" (34%).
The figures showed that of the 31,333 allegations that were investigated, only 14% were upheld, with the remaining 86% rejected.
The IPCC said there are wide inconsistencies in the way forces around the country handle complaints, pointing to figures that show:
:: The proportion of complaints initially upheld ranges from 7% to 27%
:: Some forces formally probe more than 70% of complaints, while others use more informal processes known as local resolutions in seven in 10 cases
:: Those who appeal over how their complaints are handled are twice as likely to be successful if their case is heard by the IPCC than the force
Dame Anne criticised the complaints structure.
She said: "These figures show a complaints system that is both over-complex and inconsistent, and is clearly failing to satisfy a significant number of complainants.
"Chief officers and police and crime commissioners should look closely at the figures for their own forces to satisfy themselves that complainants are being treated fairly and well.
"However, the underlying problem is the system itself."
The statistics cover complaints made about those serving with the police or about the direction and control of a force.
They are recorded by the police force in the first instance, and those who are unhappy with how their case is handled can appeal.
A regional breakdown showed that Staffordshire Police recorded the greatest annual jump in complaints, with a 66% rise from 310 in 2013/14 to 516 in the most recent year.
The Metropolitan Police, the UK's largest force, had the highest overall number of complaints with 6,828; however, this number was down by 4% on the previous year.
When allegations were compared against staff numbers, Lincolnshire had the highest rate with 580 per 1,000 employees.
Nottinghamshire upheld the highest proportion of allegations investigated, with 27%, while South Yorkshire upheld the lowest share with 7%.
Deputy Chief Constable Alan Goodwin, National Police Chiefs' Council lead for complaints, said: " We police by public consent so it is always disappointing when somebody is unhappy with the service they have received.
"We take complaints very seriously and will always listen to and take heed of those who come forward to report any dissatisfaction.
"The system for handling complaints is complex and leads to inconsistencies between forces."
Home Secretary Theresa May announced an independent review of the IPCC's structure and governance in August.
Policing Minister Mike Penning said: "These figures show the clear need for radical reform of the police complaints system.
"The police complaints system needs to be transparent and easy to understand, accountable to the public, and it must allow lessons to be learned. At the moment, as these figures show, it is too often complex, opaque and unresponsive to complainants and officers."
Superintendent Ray Marley, of the College of Policing, insisted trust and confidence in the police are "higher than ever", saying: "While the number of complaints made by the public may have risen, the number of those upheld remains low."