'Honour' crime involves violence committed by those who aim to protect the reputation of their family or community.
'Honour' crime involves violence committed by those who aim to protect the reputation of their family or community.
Honour killing is the murder of a person accused of "bringing shame" upon their family.
Victims have been killed for refusing to enter a marriage, committing adultery or being in a relationship that displeased their relatives.
In many instances, the crimes are committed by family members against a female relative.
More cases have reached the UK courts in recent years but a number of crimes still remain unresolved or undetected.
In some parts of the world, women who have been raped have also been murdered for the 'dishonour' of being a victim and the 'disgrace' it brings to their family.
Honour killing is believed to have originated from tribal customs where an allegation against a woman can be enough to defile a family's reputation - 'a life without honour is not worth living.'
Murders have sometimes taken place after a family reacted violently to their son or daughter adopting the trappings of western culture.
It's thought that up to 12 honour killings happen every year. They usually occur within South Asian and Middle Eastern families.
One of the most well-known cases is that of Banaz Mahmod, from Surrey, whose murder in 2006 was organised by her father and uncle.
She had left an unhappy arranged marriage after which she started a relationship with another man. The 20-year-old was strangled and hidden in a suitcase which was then buried underneath a Birmingham property.
The police were criticised for mis-handling Ms Mahmod's situation when she contacted them on a number of occasions before her death.
Shahien Taj, from the Henna Foundation, said: "Honour is supposed to be a positive word. Clearly, calling a killing an 'honour crime' is a contradiction of terms.
"A lot of talk and dialogue takes place after a crime has happened, but this is too little too late. If you really want to deal with an issue, you have to unpack it in its true context."
Organisations that deal with honour-based violence also help forced marriage victims, as some of those killed in the name of "honour" were trying to escape coercion into matrimony.
Laws to prevent forced marriages and provide a way out for those already in unconsented unions were introduced in England, Wales and Northern Ireland in November 2008.
Anybody convicted of trying to force someone into a marriage could be jailed for up to two years.
Within the first year, 86 Forced Marriage Protection Orders were implemented.
But as one worker who specialises in the issue said, "The sticking point is that potential victims don't want orders served on their parents - or whoever is responsible - they just want a way out of the situation."
In December 2009, the Metropolitan Police reported that there had been a huge rise in recorded incidents motivated by "honour."
They said 211 incidents had been reported in London - 129 of which were criminal offences - between April and October.
The increase may partly be due to police being instructed in September 2009 to assume honour crimes have been committed in more situations.
Nazir Afzal, from the Crown Prosecution Service, said: "It will be about making sure we look for the signs so that we don't miss cases."
Detective Chief Inspector Gerry Campbell of the Metropolitan Police told The Guardian, "Young woman are predominately the victims of honour-based violence but we are seeing an increase in young men and boys – it's now about 15% of the total numbers."
He also added that 25% of their cases involved people under the age of 18.
Honour violence occurs worldwide, from South America to Asia.
The exact figures of how many men and women have been killed in the name of 'honour' is unknown.
Not all countries keep official statistics and it's a crime that can be difficult to detect. But it's believed that the number of deaths are in the thousands.
In 2000, Asma Jahangir, a UN special rapporteur, reported that the practice of honour killings was growing.
There is concern over a rise in 'honour suicides' in Turkey since the sentence for 'honour' killers increased in 2005.
The tougher punishments may have inadvertently contributed to more female suicides occuring at the instigation of men who want to avoid longer imprisonments.
None of the world's major religions condone honour-related crimes.
But perpetrators have sometimes tried to justify their actions on religious grounds.
"Honour crime happens across the board in the Asian community," says Ram Gidoomal of the South Asian Development Partnership.
"People try to blame Muslims, Hindus or Sikhs but it tends to happen in families where there are the strongest ties and expectations. It's a very strong cultural issue."
Leaders of the world's faiths have also strongly denounced a connection between religion and honour killings.
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