Amongst the subjects discussed by the theologians of ARCIC, canon law has been conspicuously absent. The ecclesiology of koinonia, which is central to the work of ARCIC, has been of the greatest importance in �re-imagining� the Church and so promoting ecumenism. It has faced received canon law with new questions: to what extent can canon law facilitate those structures and practices which undergird the ecumenical initiatives promoted by koinonia ecclesiology? Already, canon law provides for shared institutions and chaplaincies to institutions. Test areas for future ecumenical convergence include the reception of a member of one tradition by the other, ethics and suitability for ministry. The proposed Anglican covenant presents a challenge to the canon law of member churches within the Anglican Communion and may present a model for future ecumenical convergence. The work of canon lawyers in developing this and other new models for ecumenism is indispensable to a deeper and more extensive koinonia amongst the churches.