Function composition_valid 

pub fn composition_valid(instrument: u64, proportionate: bool) -> bool

A composition (and its proportionality test) is valid only when it is anchored to an established human-rights instrument (a non-zero instrument hash) AND is proportionate. This is the structural bind: legal reasoning may not float free of a cited instrument, and a restriction must pass proportionality. (proportionate is the proportionality_met verdict.)