They settle domestic disputes, rule on financial disagreements and even grant marriages and divorces.
But Sharia courts that dish out verdicts based on hardline Islamic law operate outside our justice system.
Recent attempts by the Ministry of Justice to investigate the courts were abandoned following a lack of co-operation from Muslim elders.
The Daily Star Sunday gained unprecedented access to this secretive network, accused by Baroness Cox of using “intimidation backed by death threats”.
Last month the cross-bencher claimed they could eventually lead to the destruction of democracy, with stonings, whippings and amputations becoming common punishments.
Often based in small rooms above shops or empty flats, the courts are used by thousands of Muslims to settle a range of disputes.
Islamic clerics issue fatwas – rulings on Islamic law – and resolve issues involving business practice and deal with complaints of police brutality against Muslims.
According to research by think tank Civitas, in 2009 there were up to 85 Sharia courts across the UK.
But sources in the Muslim community claim there could now be that many in London alone.
Founded in 1985 by exiled Syrian cleric Omar Bakri Mohammed, the centre we visited in East London is one of several UK branches supervised by notorious hate preacher Anjem Choudary. Others include Luton and Derby.
Inside a basement property in Whitechapel, Choudary presides over a steady stream of Muslim devotees happy to accept his rulings rather than seek judgment from the British justice system.
Aspiring restaurant boss Abu Muslim, 20, dropped by for advice on the sale of alcohol and rules regarding the preparation of halal food.
He told us: “Just because I live in this country does not mean I am obliged to follow this (British) law. My law is Islam – the law that God has sent. If I go to the jungle tomorrow I am not going to go to the monkey for the advice.
“With the judgments they are giving out in this country, even the monkeys would give better justice. You cannot trust those people. As Muslims we can’t use any other system of law.”
Umm Aqsa visited Choudary to ask his advice on how to help her daughters, aged seven and nine, avoid the “abortion and teenage pregnancy” she believes is infecting the education system in Tower Hamlets.
The burka-clad mum said: “Girls as young as ten are getting pregnant. These things would never be allowed in Islam. I don’t want my children exposed to these things. That’s why I home school them.
“I teach my children English but I do not teach them Shakespeare. It is full of fornication. I also would not want them exposed to the evolution theory. It’s a false ideology.”
In February we revealed the cleric taught six of the nine Muslims jailed for plotting to blow up the London Stock Exchange, sparking calls from MPs for him to be arrested.
Last night the 44-year-old former lawyer, who says he does not charge people to use the courts, said: “Thanks to the network of Sharia courts Muslims have no need to engage with the British state or its institutions. This momentum, Inshallah (God willing), will eventually result in the implementation of the Sharia in Britain.”
Last month Baroness Cox spoke about the dangers of Sharia law, saying: “We do not at the moment have the most brutal punishments but there are those in this country who would like to bring them in.
“Many Sharia courts are an institutional means of intimidation backed by death threats.”