While the actual testing criteria for a diagnosis of "permanent" in the UK are quite similar to the criteria for a diagnosis of "persistent" in the US, the semantic difference imparts in the UK a legal presumption that is commonly used in court applications for ending life support. The UK diagnosis is generally only made after 12 months of observing a static vegetative state. A diagnosis of a persistent vegetative state in the US usually still requires a petitioner to prove in court that recovery is impossible by informed medical opinion, while in the UK the "permanent" diagnosis already gives the petitioner this presumption and may make the legal process less time-consuming.