Justice Secretary Kenneth Clarke has been heavily criticised for talking about "serious rape" as compared with other types of rape. But can some rapes be viewed as more serious than others?

The justice secretary's remarks suggesting some rapes were worse than others has led to a storm of protest and demands for his resignation from Labour.

Speaking to BBC Radio 5 live on Wednesday, Mr Clarke appeared to draw a distinction between date rape and "serious rape, with violence and an unwilling woman". Put to him that "rape is rape", he said: "No, it is not."

He says he used the "wrong choice of words" and insists he regards all rape as a serious crime. But can some be viewed as more serious than others?

"I come from the position that rape is rape," says criminologist Prof David Wilson of Birmingham City University, who has worked on the sex offender treatment programme at Grendon prison.

Rape statistics 13,991 recorded offences of rape of a female in England and Wales in 2009-10

recorded offences of rape of a female in England and Wales in 2009-10 1,174 recorded offences of rape of a male in England and Wales in 2009-10

recorded offences of rape of a male in England and Wales in 2009-10 2.3% of females and 0.5% of males say they have been a victim of sexual assault in the past year

of females and of males say they have been a victim of sexual assault in the past year Source: Home Office recorded crime statistics and British Crime Survey

"If we listen to what the victims of rape tell us about its impact, there is no difference between those who have suffered date rape and those who have been attacked by strangers.

"Often the victims of stranger rape will generate more sympathy, which seems to me absurd. We mustn't ever give out the message that your rape isn't as bad as someone else's rape."

Those who work with rape victims agree. They argue there is no sliding scale when it comes to the impact of rape and the violence involved.

"Rape is a man having sex without gaining permission from the woman," says Eileen Calder, who has worked with rape victims for decades and is the co-founder of the Belfast Rape Crisis Centre.

"How he does it and his relationship to the woman are insignificant. I have worked with rape victims for 26 years and violent, stranger rape is in some ways easier for women to deal with. The guilt and shame women have in a situation when extreme force hasn't been used is immense."

What I think he was trying to explain was that some offences of rape are punished more heavily than others Joshua Rozenberg, Legal analyst

Julie Bindel, a feminist campaigner who has worked with rape victims, says too often society classes "real" rape as being snatched off the street by a stranger and violently assaulted, everything else is something that just went "a bit too far".

"But I know women who have been raped by their husband or a friend and find that awful because they have been betrayed by someone they trust. The rape is attached to a part of their lives they rely on - their family or their job. It has a horrific psychological effect."

But as well as the impact of rape on the victim, Mr Clarke's comments also show a lack of understanding of what today's law actually is and how it is interpreted by judges, says Clare McGlynn, professor of law at Durham University.

In two cases this year alone the Lord Chief Justice has made a point of saying one type of rape is no less serious than another, she says. In a case in January Lord Judge told a court to approach rape within a relationship, including marriage, as "no less serious than rape by a stranger".

Image caption Clarke had been talking about plans to halve jail terms in return for a guilty plea

Again in March he spoke of a case involving multiple rapes by a husband of his wife.

"This case may have lacked extreme violence, but it certainly included significant violence," he said at the time. "As between these two features, the violence in a stranger rape case and the betrayal of trust in the relationship case, the end result is to look at the offence through the eyes of the woman who is the victim."

But Mr Clarke's defence that he used the "wrong choice of words" is understood by some. Legal analyst Joshua Rozenberg says all offences of rape are serious and he is sure the justice secretary "wishes he had said that".

"What I think he was trying to explain was that some offences of rape are punished more heavily than others, depending on whether there were aggravating or mitigating circumstances.

"The courts would never say that they treat some offences of rape more seriously than others, but they acknowledge that some offences are punished more severely."

Christopher Kinch QC, chairman of the Criminal Bar Association agrees that "aggravating features" can mean some rapists receive longer sentences, but adds that you shouldn't label certain rapes as "more serious".

"Rape is always a serious offence," he says. "It's punishable with a maximum of life imprisonment so it's one of the most serious offences on the book. There are other types of rape with more aggravating features, but it is not helpful to label them as more or less serious."

SGC rape sentencing guidelines For single offence of rape by a single offender...

For victims aged 16 and over range of 4-8 years custody (starting point five years)

For victims aged 13-15 range of 6-11 years custody (starting point eight years)

For victims under 13 range of 8-13 years custody (starting point 10 years)

Aggravating factors: Abduction, detention, abuse of trust, sustained attack, rapist knew he carried sexually transmitted infection, more than one offender, offence motivated by prejudice

Repeated rape of same victim over time has range of 13-19 years custody (starting point 15 years)

Mitigating factor: Victim engaged in consensual sexual activity with the offender on the same occasion and immediately before the offence

Maximum penalty for rape: Life imprisonment

Guidelines cover England and Wales CPS manual for sentencing guidelines

But such misplaced words have a drip, drip effect on people's attitudes, say those who work with rape victims. They say Mr Clarke's talk of "serious rape, with violence and an unwilling woman" just fuels society's preoccupation with the physical violence involved in a rape.

"Most people don't believe a woman unless she has a black eye or a split lip, some obvious sign to suggest something happened that wasn't very nice," says Bindel. "But women can have very significant physical injuries you can't see... internal injuries. Then there is the psychological hurt.

"There is a real mythology about rape - that it's extremely rare and the perpetrators are crazed strangers who strike on a dark night. People don't want to accept that ordinary men can rape."

Calder agrees: "People separate rape from reality, think of it as a horrendous crime that happens to someone else. If they think of it in this way it takes away the fact that any man can be a rapist."

Reporting by Denise Winterman, Tom de Castella, and Jon Kelly