Only a fraction of investigations into forced marriage in the UK result in suspects being charged, according to police figures obtained by the Guardian.
Just five of the 51 cases investigated in West Yorkshire since June 2014 have resulted in a suspect being charged.
A boy as young as eight is among the number of children that judges fear are at risk of forced marriage, the Guardian found.
Many cases are dropped due to victims being too afraid to give evidence.
Of the 51 cases, 35 were dropped due to "evidential difficulties", 16 of which were due to "victim-based" problems.
Britain's most senior Muslim police chief, commander Mak Chishty has spoken out against forced marriage and encouraged members of the Muslim community to "no longer deny" its existence.
"My message to the community and to victims is I recognise it's underreported, I recognise it's going on. I need you – through friends, family, teachers – to come and tell me and my colleagues in policing so we can help," he told the Guardian.
"I also appeal to the wider community to say actually this practice is out of date, it is abuse and it must be stopped. That doesn't mean not practising your religion, this means conforming with human rights."
He reiterated that "it's not about disrespecting any culture", highlighting he is from a Muslim Pakistan background. "This is about a human being, their human values, their human rights and us being able to protect them," he said.
Forced marriage was officially criminalised in June 2014 under the Anti-social Behaviour, Crime and Policing Act. It was hoped this would encourage victims to come forward.
There has been one conviction in the West Midlands under the new law.
In that case, a businessman secretly filmed a devout Muslim woman showering and blackmailed her into marriage. He was then sentenced to 16 years for multiple charges, including rape, bigamy, voyeurism and forced marriage.
