Crown prosecutors are facing "unsustainable" budget cuts, with some warning that financial pressures will lead to lighter sentences.

A change to how the Crown Prosecution Service is funded will cut 25 per cent from its overall budget over the course of four years, with the Palmerston North region losing almost half.

Pressure to get rid of cases cheaply could result in an increase in plea bargains, and the "disposal" of cases, where the Crown offers no evidence, critics fear.

Documents released to The Dominion Post under the Official Information Act show dozens of emails and letters from concerned solicitors, worried at how they will work within tighter budgets.

New Plymouth Crown Solicitor Cherie Clarke described the cuts as "unreasonable and unsustainable". There was a risk of judging regional warrants by how quickly they were getting cases through court.

"I have a real concern from what I am hearing from others in the network, that there will be differences in approach in order to reduce costs, and those motivated more by the ‘bottom line' could be perceived to be more efficient merely on the figures produced, rather than the quality of prosecution service."

The funding changes are part of a suite of cuts across the justice sector that will see the CPS budget slashed by 25 per cent, from $42m to $31.5m, by 2014-15.

Wellington faces cuts of 25 per cent, while Palmerston North's funding will be slashed by 47 per cent.

Funding in Auckland will drop 44 per cent by 2015-16 from its 2011-12 level. Auckland firm Meredith Connell has lost two senior Crown prosecutors since the changes took place.

Renowned child abuse prosecutor Phil Hamlin was forced out of the firm two weeks ago and Ross Burns, who prosecuted the Urewera raids trial and the Occupy Auckland protesters, has retired.

Meredith Connell stands to lose $7.5 million a year by 2015, which Auckland Crown Solicitor Simon Moore, QC, described in an email to overseeing agency Crown Law as potentially "catastrophic".

Mr Hamlin is one of the most experienced child abuse and child murder prosecutors. He said he did not want to leave the firm but was forced out.

There were several reasons, but money was "the background factor". There had been huge cuts to funding, and they were having consequences.

"There was less money available for all of us. My fellow partners weren't prepared to share."

A spokeswoman for Solicitor-General Mike Heron, QC, agreed the budget cuts would encourage prosecutors to push for earlier resolutions, but did not believe that would result in rushed or inferior outcomes.

"Crown solicitors have given assurances they and their firms can continue to provide prosecution services without a reduction in quality.

"The funding cuts which the Crown is experiencing obviously mean that there is a benefit in early pleas of guilty . . . [but the] objective of securing early resolutions is as much about securing better outcomes for victims, witnesses and accused as it is about creating efficiencies within the criminal justice system.

"Speedy justice is better for everyone."

But Sensible Sentencing Trust spokesman Garth McVicar said: "The whole integrity of our justice system has been built around the belief that the Crown takes over the pursuit of justice on behalf of the victim.

"We're going to end up with a system that the public and the victims have no faith in."

He was told solicitors had approached the attorney-general's office with concerns, but "they've basically been told ‘suck it or lump it'."

Consultant John Spencer, who was commissioned to review the Crown Prosecution Service in 2011, told The Dominion Post he was concerned the budget cuts could diminish the quality of lawyers willing to work for the Crown. "My major concern is that it may lead to a lesser quality of prosecution and make it difficult to attract the right calibre of person to be Crown prosecutors.

"At the end of the day, you get what you pay for."

FUNDING REDUCTIONS

Auckland 2011-12 – $17.8m, 2015-16 – $9.87m

Christchurch 2011-12 – $3.27m, 2015-16 – $2.73m

Napier 2011-12 - $.93m, 2015-16 – $1.2m

Palmerston North 2011-12 – $1.4m, 2015-16 – $.86m

Wellington 2011-12 – $4.19m, 2015-16 – $3.13m