By Dominic Casciani
BBC News community affairs
Tough government rules on whether some immigrants can marry in the UK are being challenged in the High Court.
Arrests: Suspected sham marriage targeted
Immigration campaigners say the law is discriminatory and want it overturned on human rights grounds.
The Home Office introduced the rules last year saying they were essential to crack down on sham marriages for immigration.
Under the rules, the Home Secretary has the power to block a proposed marriage if he believes it may be bogus.
The rules mean people born outside of the EU and some bordering European nations who have only six months' permission to be in the UK must seek special permission from the Home Office to marry, irrespective of the status of their partner.
The application costs £135 and marriages can only take place at specially-selected register offices.
SUSPECT MARRIAGES REPORTED BY REGISTRARS
Note: 2005 figures incomplete; new law came into force in February. Source: Home Office
The only exemption is for people who marry in the Church of England.
The first of three test cases involves a foreign national from outside Europe who wanted to marry someone from within the "European Economic Area" (EEA) who was legally living in the UK.
The two other cases relate to asylum seekers, including one whose case had been turned down but wanted to marry someone already given protection as a refugee.
Habib Rahman of the Joint Council for the Welfare of Immigrants said the law discriminated against genuine couples.
"The Home Secretary is now the Marriage Registrar of last resort," he said.
"These rules breach people's European Convention rights and are breaking the hearts of many genuine couples who have contacted the JCWI.
"At the same time the latest figures show the rules are acting as a money-making machine for the Home Office."
Nobody knows the scale of sham marriages, although senior registrars suggested that before the new legislation there could have been at least 10,000 a year.
Registrars at Brent Council in north London, one of the most diverse areas of Britain, suggested in 2005 that a fifth of all marriages there were bogus, with officials able to spot couples who barely knew each other.
One 2005 case saw 25 people jailed for a sham marriage network stretching from London to Leicester.
According to Home Office figures, sham marriages had been rising before the new law - and fell dramatically when it was introduced.
A spokesman told BBC News: "Urgent action was needed to tackle the growing problem of abuse.
"The government is determined to protect the UK's immigration system and marriage laws."