Lau, 34, is accused – with nine others – of infractions against the law on freedom of assembly over the group of high-vis-vest-wearing Islamists who declared that they would patrol the streets to police morals last September.
The German convert to Islam and leading fundamentalist preacher had declared himself to be one of the leaders of the group in a video published online.
'Sharia police' members showing off their uniforms in a photo published online.
Eleven of the group's members were prosecuted for unlawful assembly and wearing illegal uniforms in public shortly before Lau announced that he would re-brand his organization 'Pro Halal'.
But his actions had already created national outrage and prompted politicians to declare any system of parallel justice to be beyond the pale.
"Sharia law is not tolerated on German soil," Interior Minister Thomas de Maiziere said at the time.
Hotspot for fundamentalism
The western state of North Rhine-Westphalia (NRW) is widely regarded as a hotspot for fundamentalist Islam in Germany.
A number of high-profile German 'foreign fighters' who have joined Isis in Iraq or Syria came from the country's most densely populated region.
"[Isis] calls on young people in NRW in a targeted way to join their fighters and help erect a so-called holy state," state interior minister Ralf Jäger wrote in a brochure titled Salafism as Youth Culture.
And a trial began last September against a group of four Salafists (fundamentalist Sunni Muslims) accused of planting a bomb at the central station in Bonn.
Last year's annual report from the state branch of the Office for the Protection of the Constitution (VS) found that "the risk in the area of Islamic-motivated extremism in NRW dramatically spiked in 2014".
VS agents were tracking more than 160 people in the state in January 2015, when the report was written.
But in their zeal to defend against extremism, some politicians in the state have offended ordinary Muslims – for example, by trying to 'counter' handouts of free Korans by handing out copies of the German Constitution on the same day earlier this year.