This document summarizes situations where the threat of a contract being declared ineffective should be considered in procurement decision making. Some key areas discussed include: 1) Decisions made in good faith around whether a contract requires an OJEU advert could potentially result in a contract being declared ineffective if the decision is later deemed incorrect. 2) Scope changes to a procurement may treat it as a direct award if it evolves outwith the original advert scope. 3) The classification of services and whether contracts meet value thresholds can be difficult judgements, with ineffectiveness risk increasing for decisions near the margins. 4) Significant changes to contractors or subcontractors after award may require a new competition to avoid