One of the striking aspects of the free software community is its obsession with licences. It's as if within every hacker there's a lawyer struggling to get out. But maybe it's not so surprising; as Larry Lessig reminded us, “code is law”, and the reverse is also true in the sense that the licence adopted has a big impact on how the software is produced. That explains, in part, why recent discussions of Oracle's proposed acquisition of Sun – and hence MySQL – have once more put free software licences under the microscope.