R v Chargot (trading as Contract Services) [2008] UKHL 73, [2008] All ER (D) 106 (Dec)
When criminal proceedings are brought against an employer under ss 2 and 3 of the Health and Safety at Work Act 1974, it is sufficient for the prosecution to prove merely a risk of injury arising from a state of affairs at work (it is not necessary to prove specific breaches of duty by the employer). The onus then passes to the employer to make good the defence of reasonable practicability.