NATO's intervention in Kosovo in 1999 (Operation Allied Force) is one of the seminal events in contemporary international relations. While the humanitarian aspect of this intervention was widely endorsed the dominant view is that NATO acted illegally. Many who acknowledged this illegality, however, argued that because Operation Allied Force had so emphatically illustrated deficiencies with the existing legal regime that legal reform would subsequently follow. This article examines whether 10 years on Operation Allied Force can be considered a legal precedent. It is argued that while Operation Allied Force was unquestionably of significant political importance it does not constitute a legal precedent. While the intervention sparked much legal debate it did not did not lead to any significant addition or amendment to positive law nor does it constitute a precedent for customary international law.