It’s probably not helpful to think of it as overturning the concept of innocent till proven guilty or reversing the burden of proof. Rather it is an inevitable (and appropriate) consequence of modern safety legislation which is goal based and not prescriptive. In other words the legislation requires for example that employers provide safe work equipment or that buildings are constructed to resist the spread of fire. To demand that of employers and builders etc. is unduly onerous unless they are given some guidance or benchmark which they can follow, rather than having to start with a blank sheet of paper and literally figure everything out for themselves from scratch. So the approved documents and codes of practice give them statutory guidance which they can follow and rely on. It’s quite reasonable to say that if they choose to depart from that guidance and do something different, then they should be the ones who have to show that what they did was no worse than if they had followed the statutory guidance. This allows new technology to be introduced, which may be a major improvement on previous practice, but it is only reasonable that those who introduce new technology and practices are responsible for demonstrating that they are as good or better than previous practice.

I suspect one of the issues for the police and CPS regarding any manslaughter prosecution for Grenfell will be that the ‘loophole’ in ADB which supposedly allowed combustible cladding to be used because its function was not insulation (but instead weatherproofing/aesthetic), may make it very difficult to get a conviction for unlawful act manslaughter (if the act of specifying/installing combustible cladding was not unlawful, i.e. a criminal act under Building Regs, then one of the essential requirements for an unlawful act manslaughter conviction is absent).

However, if it is clear from the records and other evidence that the combustible cladding was chosen in the knowledge that they were exploiting a legal loophole, that itself may be evidence of gross negligence manslaughter, i.e. they knew damn well the prohibition on combustible cladding (in insulation) on buildings of that height was for very good reasons of fire safety, and deliberately exploiting that loophole is itself prima facie evidence of gross negligence manslaughter.