Police attempts to meet targets have led to serial and even violent offenders getting off lightly, lawyers and magistrates said on Thursday.
They are worried police are using on-the-spot fines and cautions as well as downgrading offences to avoid going to court - what one lawyer called tantamount to "throwaway justice".
Deputy Chairman of the Magistrates' Association John Howson said he was particularly worried serious offences were not being dealt with rigorously enough, because police wanted to reduce their workload.
"We're concerned about undercharging - where assault causing actual bodily harm is charged as common assault," Howson told the BBC.
"We also wonder whether common assault offenders are being given fixed penalties and not brought to court. Anyone who commits an act of violence should be in front of the court and not given a fixed penalty.
"Likewise burglary is a serious crime and should be in front of the court and not, at the end of a shift, being charged to meet a target or because the paperwork is easier."
Howson said the tendency was leading to an "alternative justice system," noting that in 2007 over 700,000 people were convicted in court, while 650,000 were given on-the-spot fines and cautions.
Nottingham solicitor Digby Johnson said: "We've come across offences of theft where the same person might have been into two or three different police stations in the course of a two-week period and on each occasion they have walked out with a fixed penalty notice."
"It undermines the whole criminal process. It's justice on the cheap - it's almost throwaway justice, because that's what happens to a lot of the notices when they are given out."
The Ministry of Justice rejected the concerns.
"Since 1997, crime has fallen by more than a third," it said in a statement.
"Those who commit crime now have a greater chance of being convicted and the number of offenders brought to justice has increased dramatically.
"It's not always necessary for an offender to be taken to court for an offence to be dealt with effectively and to the satisfaction of the victim.
"Fixed penalty notices or cautions enable police to deal swiftly with low-level offending, freeing them up to spend more time on frontline duties and more time investigating violent, dangerous or sexual offences as well as freeing up court time for more serious offences."
