As we reported briefly in December, the Greek Council of State [Symvoulio tis Epikrateias] sought an advisory opinion from the CJEU on whether it was compatible with Directive 98/5/EC (on mutual recognition of legal qualifications) for the Athens Bar Association to refuse to register Brother Eirinaios, a monk qualified as a lawyer in Cyprus and a member of the Cyprus Bar Association, to practise in Greece under his home-country professional credentials – on the ground that monks simply could not, under Greek national law, be entered in the registers of bar associations. The decision of the Athens Bar Association was based on Article 8(1) of a Presidential Decree that provides that the Greek national rules on incompatibilities (specifically, being a cleric or a monk) also apply to lawyers from other EU jurisdictions who want to practise in Greece. The Council of State stayed the proceedings and referred the following question to the CJEU for an advisory opinion:
“Is Article 3 of Directive [98/5] to be interpreted as meaning that the registration of a monk of the Church of Greece as a lawyer with the competent authority of a Member State other than that in which he obtained his professional qualification, in order for him to practise there under his home-country professional title, may be prohibited by the national legislature on the ground that monks of the Church of Greece cannot, under national law, be entered in the registers of bar associations since, on account of their status as persons under monastic discipline, they do not provide certain guarantees necessary for practice as a lawyer?” .
In Monachos Eirinaios  EUECJ C-431/17_O, Advocate General Sharpston advised that Directive 98/5/EC does not permit a Member State automatically to ban a person qualified in his home-country “on the grounds that, as a person under religious discipline, he cannot by definition conduct himself in the manner required to provide the guarantees necessary for practice as a lawyer”.
In Monachos Eirinaios v Dikigorikos Syllogos Athinon  EUECJ C-431/17, the Court agreed with AG Sharpston. The Court noted that Directive 98/5/EC establishes a mechanism for the mutual recognition of the professional titles of migrant lawyers wishing to practise under the professional title obtained in their home Member State, harmonising fully the preconditions for the exercise of the right of establishment conferred by the Directive.
The Court had already held that the presentation to the competent authority of the host Member State of a certificate attesting to registration with the competent authority of the home Member State was the only condition for registration . The national legislature could not, therefore, make additional conditions over and above the basic precondition for registration . There was a distinction to be drawn between registration with the competent authority of the host Member State, which was subject solely to the condition of presentation of a certificate attesting to registration with the competent authority of the home Member State, and the practice of the profession of lawyer in the host Member State, in respect of which the lawyer was subject to the rules of professional conduct applicable in that Member State .
Rules of professional conduct had not been harmonised and might, therefore, differ considerably between Member States and it was also permissible for a national legislature to prescribe guarantees; however, those guarantees were not permitted to go beyond what was necessary in order to attain the objectives pursued . To comply with EU law, rules of professional conduct applicable in the host Member State had to be proportionate ; and it was for the Council of State [Symvoulio tis Epikrateias] to carry out the necessary checks as to the compatibility of the rule at issue.
The Grand Chamber ruled as follows:
Article 3(2) of Directive 98/5/EC of the European Parliament and of the Council of 16 February 1998 to facilitate practice of the profession of lawyer on a permanent basis in a Member State other than that in which the qualification was obtained must be interpreted as precluding national legislation which, on account of the incompatibility under that legislation between the status of monk and practice of the profession of lawyer, prohibits a lawyer who has the status of monk, and who is registered as a lawyer with the competent authority of the home Member State, from registering with the competent authority of the host Member State in order to practise there under his home-country professional title. 
Which should come as no great surprise to anyone.