Wikipedia
Ad vitam aut culpam is a Latin phrase found in Scots law which meaning "for life or until fault" which guarantees the right of a Sheriff Depute ( judge) to hold office permanently or until they forfeit such by misconduct. The Heritable Jurisdictions (Scotland) Act 1746 used the phrase to guarantee a Sheriff's term office after they have held office for seven years.
The applicability of this law was decided upon by the House of Lords in the case Stewart v. Secretary of State For Scotland where it was stated this it did not protect a Sheriff from dismissal for inability. Further Acts of Parliament empowered the Lord President of the Court of Session and the Lord Justice Clerk to remove Sheriffs from office due to a personal inability to complete their function - differentiated from a mental incapacity or incapacity due to age. Therefore, ad vitam aut culpum has a limited applicability which does protect an office from dismissal if they are incompetent.