Most people will agree that the message of Christ is a call to action. Whilst the form of response may vary from contemplative or intercessor prayer to public forms of apostolate and ministry, the call of Christ represents an invitation; one which demands a response. Within the Catholic tradition, the common or shared vocation comprises the universal call to holiness. It is a call which finds fulfilment in communion. The Conciliar teaching on the complex reality of the Church as organic structure and mystical body makes clear that the Church fulfils an irreplaceable role as 'the sacrament of inner union of men with God' (CCC 775). Through baptism we are reborn in Christ and reject the enticements of the enemy and all those things which would separate us from the love of God; promises we renew during the Easter liturgies. These promises, and our participation in the profession of faith and the reception of the sacraments, evidence our membership of and communion with the Church. The result is a shared endeavour; a community of purposes; in which the role of each is determined in line with canonical condition. The Code of Canon Law encapsulates this self-understanding of the Church community in the term 'people of God' (populo Dei). However, the populo Dei is not reducible to the status of some friendly association or members' club. Rather, the Church's mission and sacramental character necessarily means that the laws which the Church promulgates must be consistent with its own doctrine, ecclesiology, and eschatological purpose. Within the Code of Canon Law the Church declares its jurisdiction over itself and does so in terms of exclusivity (e.g. c1401). Despite depictions to the contrary this does not per se place the Church in opposition to secular authorities. Article 9 of the European Convention on Human Rights 1950 expressly declares the fundamental right of freedom of conscience and belief. These rights are recognised as being enjoyed at both individual and communal level. At the level of institution, faith communities are acknowledged as possessing rights of autonomy or self-determination. Within the English Common Law, decisions attest to the preparedness of the secular courts to accommodate issues of belief and indeed, the perception that it is no part of the secular law to authenticate mattes of belief. See: R v Secretary of State ex p Williamson  UKHL 15 and the family case of AI v MT  EWHC 100 (Fam). These authorities point to the potential for collaboration and opportunity. However, a more nuanced perspective is provided in Sherghill and Ors v Kheira and Ors  UKSC 33. In delivering the lead speech in that case, Lord Neuberger opined:
"46. The law treats religious organisations as voluntary associations. It views the constitution of a voluntary religious association as a civil contract as it does the contract of association of a secular body...The Courts will not adjudicate on the decisions of an association's governing bodies unless there is a question of infringement of a civil right or interest...
"47. The governing bodies of a religious voluntary association obtain their powers over its members by contract. They must act within the powers conferred by the association's contractual constitution..."
Where does this leave us? From a constitutional perspective, the Church relies primarily on the Code of Code Law. It is nonetheless supplemented by customs, practices, particular laws and indeed, transactional documentation which is adopted at both diocesan and parish level. Within the English Law, the contractual entitlements of the parties to a contract are determined by the intention which may be attributed to them; viewed from the vantage point of the objective by-stander. This forensic umpire is required to posit and resolve the question: what is each reasonably entitled to expect from the other? This requires not only the interpretation of documentation issued to particular persons, but the evaluation of that material within a factual matrix (i.e. the real life setting in which the transaction was intended to take effect). This state of the law now requires all faith communities within these islands to cultivate more detailed and conscious deliberation regarding the adoption of contractual obligations, the inception of relationships, the principles by reference to which disputes may be resolved; in each case ensuring that the documentation and praxis enjoys a symmetry with the Church's own ecclesiology, doctrine and mission. Any ambiguity of the pressing need for such a re-evaluation has been removed by the duties of data controllers under the General Data Protection Directive (GDPR). A failure to engage with this task not only imperils the position of the Church in the given transaction, but stands as an invitation to the secular courts to disregard those essential characteristics which define the Church and distinguish it from those associations seeking to fulfil more secular ambitions.