Only locally licensed lawyers can be partners in a law firm. Slovenian/EU/EEA/Swiss citizenship is required to become a licensed lawyer. Foreign licensed lawyers from third (non-EU) countries may exercise only subject to material reciprocity. 
"Article 2
As part of the practice of the legal profession, a lawyer provides legal advice, represents and defends clients before courts and other state bodies, draws up documents and represents clients in their legal relations.
Only a lawyer may represent a party against payment in court, unless otherwise provided by law.
Article 2a
A foreign lawyer who has acquired the right to practice law in his home country may, under the conditions determined by this Act, practice in the Republic of Slovenia:
- legal services under professional title from their home country in accordance with Directive 77/249 / EEC,
- the legal profession under the professional title of his home country in accordance with Directive 98/5 / EC,
- the legal profession called "lawyer".
Home is the country in which a lawyer has the right to practice law under a professional title obtained in accordance with the regulations of that country.
Under this Act, a lawyer from another country which is a Member State of the European Union, the European Economic Area or the Swiss Confederation is a lawyer entitled to practice law in any Member State of the European Union, the European Economic Area or the Swiss Confederation under a professional title under the regulations of that country.
[...]
Article 25
A lawyer can be someone who meets the following conditions:
1. that he is a citizen of the Republic of Slovenia, another Member State of the European Union, the European Economic Area or the Swiss Confederation, [...]
A foreign citizen who meets the conditions for practicing law under the law of the country of which he is a citizen shall, if reciprocity apply, enter himself in the register of lawyers who may practice law before state bodies in the Republic of Slovenia:
1. if he passes the mock exam on knowledge of the legal order of the Republic of Slovenia according to a special law,
2. (deleted)
3. (deleted).
[...]
Article 34f
A lawyer from another country other than a Member State of the European Union, the European Economic Area or the Swiss Confederation who has the right to practice law in a country not a member of the European Union, the European Economic Area or the Swiss Confederation may practice law or practice under the conditions, which are determined by this Act for lawyers from another country, which is a Member State of the European Union, the European Economic Area or the Swiss Confederation, in Article 34.a of this Act, if the condition of actual reciprocity is met.
[...]
Article 37
The activity of a law firm is limited to the practice of the legal profession.
The amalgamation of law firms for the purpose of joint practice of law is not permitted.
The partners of a law firm may only be lawyers who practice law in a law firm. Partners may not practice law in other law firms.
The management of a law firm cannot be entrusted to a person who is not a lawyer.
A limited liability law firm must have an office at its registered office in which at least one partner practices law.
The law firm is obliged to notify the Bar Association of Slovenia of any change in the articles of association, the partner or the person authorized to represent, as well as the establishment or termination of the branch.[...]" (Law on Advocacy (Official Gazette of the Republic of Slovenia, nos. 18/93), last amended on 7 June 2019, Articles 2, 2a, 25, 34f and 37 [google translation])
Law on Advocacy (Official Gazette of the Republic of Slovenia, nos. 18/93), last amended on 7 June 2019, Articles 2, 2a, 25, 34f and 37
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