More than 2,000 suspected criminals avoided prosecution last year because of their ill-health or age, official figures have shown.
The Crown Prosecution Service (CPS) revealed 1,892 criminal cases were dropped at courts in England and Wales in 2014 due to the "significant ill-health, elderliness or youth" of a defendant.
Another 439 cases were abandoned for the same reasons before the suspect was charged with an offence, according to figures obtained by the Press Association.
The figures come after the CPS decided not pursue child sex abuse charges against Lord Janner because he suffers with dementia, before the decision was overturned following a review.
An Old Bailey judge will rule on December 7 whether the 87-year-old peer is well enough to stand trial.
Mark Shelton, whose former headmaster Colin Cope was considered too unwell to stand trial on sex abuse charges, said the CPS had "failed in their duty to prosecute".
Mr Shelton, who waived his right to anonymity, said: "I'm not surprised by the figures. This is just the tip of the iceberg.
"I don't feel justice has been done. The CPS failed in their duty to prosecute. I don't know where to turn any more."
A judge ruled that Cope, a former headmaster accused of sexually abusing boys at Tettenhall College in Wolverhampton in the 1970s, was too unwell to stand trial at Shrewsbury Crown Court in 2009. Cope died in March this year, aged 84.
Victim Support said it was "critical" that any decision not to prosecute suspected criminals was "properly explained" to those involved in the case.
The charity's chief executive Mark Castle said: "Victims often fear that they will not be believed, so it can be many years before they come forward.
"It is critical that victims have the reasons behind a decision not to prosecute properly explained to them so that they understand that it does not mean they have not been believed."
The CPS said it could not reveal how many cases were dropped solely because of a defendant's physical or mental condition because they were recorded under a single category of "significant ill-health, elderliness and youth".
The figures for 2014 are higher than in previous years, although the CPS has only included "youth" cases in the category since April 2013.
According to the figures released under the Freedom of Information Act, 1,714 prosecutions were dropped at court because of a defendant's ill-health or age in 2013, compared with 1,402 in 2012.
Meanwhile 354 cases were dropped under the same category before the suspect was charged in 2013, along with 128 cases in 2012
Some 516 prosecutions were dropped at court because of a defendant's age or ill-health between January and March this year, while another 132 cases were dropped before a suspect was charged.
The CPS said the number of cases dropped in court due to a defendant's ill-health, elderliness or youth represented 0.3% of all prosecutions last year.
A CPS spokeswoman said: "Each individual decision to prosecute is made if there is both sufficient evidence to do so and a prosecution is in the public interest.
"The Code for Crown Prosecutors recognises that the more serious the offence, the more likely it is that a prosecution is required, and the age or ill-health of a defendant will be taken into account when deciding whether to prosecute."
In relation to Mr Cope's case, the CPS said it opposed an application to halt the court proceedings against him.
The application was made on the basis that he would not have a fair trial due to the passage of time since the alleged offences and due to his state of health, it added.
A CPS spokeswoman added: "It was never the CPS' view that the defendant should not stand trial due to his age or ill-health as the (alleged) offences were very serious."