Ab Initio
Latin for 'from the beginning'. Used to describe something treated as invalid, or as never having had legal effect, from the moment it was purportedly made — as opposed to being set aside only from some later date.
Independent editorial summary — not the official statute text. Read the official version on legislation.gov.uk.
Courts most often reach for the phrase when explaining what actually happens to a decision once it has been successfully challenged. The Administrative Court Guide, in describing the effect of a quashing order in judicial review, explains that a successful challenge means the 'decision does not have legal force or effect. It is also treated as if it' never had such force or effect, and continues: 'It is sometimes said that a quashed decision is void ab initio (i.e. from the beginning).'
The distinction the courts are drawing matters in practice. Something that is void ab initio is treated as never having had any legal existence at all, so far as the law is concerned, rather than as valid until a court intervenes and invalid only from that point forward. That is why, after a quashing order, the ordinary next step is for the matter to be sent back to the original decision-maker to be decided afresh — the flawed decision is not merely cancelled going forward, it is treated as though it was never validly made in the first place.
Related terms
Official sources
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