Most claims for social security benefits in Britain are determined by relatively junior civil servants, known as adjudication officers, who work in the local offices of the Department of Social Security.' Claims for unemployment benefit are decided by adjudication officers working within the Department of Employment, and some benefits (for example, child benefit and family credit) are handled centrally. A dissatisfied claimant has the right of appeal to a social security appeal tribunal, consisting of a chairperson and two lay members, which must then hold an oral hearing of the appeal. A further right of appeal lies to the Social Security Commissioners, and from there to the ordinary courts, but such appeals are restricted to points of law.2 In practice, the vast majority of appeals do not proceed beyond the tribunal stage.3 At the tribunal, the adjudication officer who took the original decision has a right to appear in the guise of a presenting officer.4 The presenting officer who appears before the tribunal need not be the individual adjudication officer responsible for the decision under appeal. For income support cases the functions of initial decision making and any subsequent appeals work are kept separate. The appeal is presented by a specialist appeals officer, whose job involves processing all income support appeals received within a particular local office. Where contributory benefits are concerned (for example, invalidity benefit or unemployment benefit), the handling of appeals, including acting as presenting officer before tribunals, remains the responsibility of the adjudication officer. In either event the presenting officer, like the claimant, has the right at the tribunal to be present and to call and question witnesses.5 Based on recent research, this article analyses the ambiguous and ambivalent role played by presenting officers before social security appeal tribunals. To set our findings in context, it is necessary to outline the fundamental changes in the social security appeals system that the last two decades have witnessed. In 1975 the Bell report catalogued a series of deficiencies in the standards ofjustice attained by supplementary benefit appeal tribunals.6 Bell's recommendations led to a phased programme of reforms in the late 1970s and early 1980s.7 Amongst the most significant of these measures were