Up to 2021, law firms could be created only by Luxembourg or EU licensed lawyers. In principle, only nationals of Luxembourg and of other EU states could become licensed lawyers. Third-country nationals were exceptionally authorised to obtain a license and participate in a law firm subject to reciprocity.
Since 2021, nationality and reciprocity conditions are no longer a pre-requisite for admission to the legal profession.  
"Art. 2.
(1) Lawyers alone may assist or represent the parties, apply and plead for them before courts of any nature whatsoever, receive their documents and titles in order to represent them to judges, carry out and sign the acts necessary for regularity of the procedure and put the case ready to receive judgment.
The provisions of the preceding paragraph do not prevent the application of special legislative provisions and the faculty:
a)	insured persons to be represented or assisted, before the Social Security Arbitration Council or the Higher Social Security Council, by a delegate of their professional or trade union organization, their spouse or partner within the meaning of the amended law of July 9 2004 relating to the legal effects of certain partnerships, their relatives or allies in the direct line or their relatives or allies in the collateral line up to the third degree inclusive; representatives must demonstrate special power;
b)	the National Health Fund, the Sickness Fund for civil servants and public employees, the Sickness Fund for civil servants and municipal employees, the Mutual Medical Assistance of the Luxembourg National Railway Company, the Employers' Mutuality, of the Accident Insurance Association, the National Pension Insurance Fund, the Compensation Fund, the National Family Benefits Fund, the Joint Social Security Center, the National Solidarity Fund, social and welfare offices any other administration or service of the State to be represented or assisted by one of their agents, duly authorized by the relevant minister respectively the president of the body concerned, before the Social Security Arbitration Council or the Superior Council of social Security;
c)	litigants to act by themselves or to be represented or assisted by a chartered accountant or a company auditor, duly authorized to practice his profession, before the administrative court called to hear an appeal regarding contributions direct;
d)	of the State, municipalities and other legal entities under public law to be represented or assisted by a duly authorized official or agent of their administration, before the justice of the peace, before the president of the district court or the judge who replaces him, ruling on summary proceedings;
e)	of the public prosecutor, to represent parties in court in the cases provided for by law.
(2) No one may, directly or through an intermediary, give, on a regular basis and for remuneration, legal consultations, or draw up documents under private signature for others, if he is not authorized under the terms of this law , to practice the profession of lawyer.
[...]
Article 5
No one may practice the profession of lawyer unless they have obtained registration on the roll of a Bar Association established in the Grand Duchy of Luxembourg.
Article 6
(1) To be entered on the roll as a lawyer practicing in an individual capacity, you must:
a)	present the necessary guarantee of good repute.
b)	Proof of the fulfillment of the conditions of admission to the internship or fulfill the conditions to be registered as a lawyer practicing in the Grand Duchy of Luxembourg under his original professional title, in application of the law of November 13, 2002 transposing into Luxembourg law of Directive 98/5/EC of the European Parliament and of the Council of February 16, 1998 aimed at facilitating the permanent exercise of the profession of lawyer in a Member State other than that where the qualification was acquired.
Exceptionally, the Council of the Order may exempt people who have completed their professional internship in their State of origin and can attest to professional practice of at least five years, from certain conditions of admission to the internship.
c) [repealed by  Law of 20 July 2021, Mém. A627]  	
d)	master the language of legislation and administrative and judicial languages ​​within the meaning of the law of February 24, 1984 on the language regime without prejudice to article 31-1. The level of skills to be achieved for the Luxembourgish and German languages ​​is level B2 of the Common European Framework of Reference for oral comprehension and level B1 for oral expression and for the German language level B2 for written comprehension. For the French language, level B2 of the same framework is required both for comprehension and for written and oral expression.
By way of derogation from the preceding paragraph, European lawyers referred to in Article 10 of Directive 98/5/EC of the European Parliament and of the Council of 16 February 1998 aimed at facilitating the permanent exercise of the profession of lawyer in a Member State other than that where the qualification was acquired as well as lawyers covered by Directive 2005/36/EC of the European Parliament and of the Council of September 7, 2005 relating to the recognition of professional qualifications as amended by Directive 2013/ 55/EU of the European Parliament and of the Council of November 20, 2013, at the time of their admission to list I of the roll of a Bar Association must master the language of the legislation within the meaning of the law of February 24, 1984 on the regime languages ​​to the extent that they limit their professional activities to those which do not require mastery of other languages ​​within the meaning of the law of February 24, 1984 . The level of language knowledge required is that indicated in the preceding paragraph.
(2) Before being registered on the roll of lawyers, candidate lawyers, upon presentation by the President of the Order or his delegate, take the oath before the Court of Cassation in these terms “I swear loyalty to the Grand Duke, obedience to the Constitution and laws of the State; not to deviate from the respect due to the courts; not to advise or defend any cause that I do not believe is right in my soul and conscience.
[...]
Art. 34.
(1) Lawyers may associate with each other within a lawyers' association. They can also associate themselves within a legal entity under Luxembourg law or foreign law.
(2) All partners in an association of lawyers or in a legal entity practicing the profession of lawyer must be lawyers registered with a Bar or an organization representing the competent authority of a Member State of the European Union .
The Council of the Order may authorize association with lawyers registered with an Order or an organization representing the professional authority of a non-member State of the European Union on the condition of noting that this Order or this organization ensures conditions of registration, exercise of the profession and association equivalent to those provided for in this law.
Art. 34-1.
(1) The partners of an association of lawyers decide on the legal form and terms of their association, its representation with regard to third parties and the rights and duties of the partners.
(2) Within two weeks of the conclusion of the association contract or the amending act, a copy is sent by registered letter to the Council of the Order which may, within one month of receipt, give formal notice to the associated lawyers to modify the agreement so that it complies with professional rules. The associated lawyers may appeal this decision to the Disciplinary and Administrative Council by request within forty days of sending the decision.
[...]
Art. 34-3.
(1) Legal entities under Luxembourg law or foreign law admitted to the roll of an Order have as sole activity the exercise of the profession of lawyer.
(2) The name of the legal entity must be followed or preceded by the legal form in which it is organized and if it acts through its establishment in Luxembourg, by the words “registered with the bar of Luxembourg/Diekirch”.
(3) The securities representing the capital of the legal entity under Luxembourg law or foreign law practicing the profession of lawyer must be nominative and can only be held by a person meeting the conditions to be a partner in a legal entity practicing the profession lawyer in the Grand Duchy of Luxembourg.
(4) The constitutive documents of any legal entity practicing the profession of lawyer in the Grand Duchy of Luxembourg must include:
- the terms of the transfer of shares or shares inter vivos or upon death;
- the rights and obligations of the partner who has lost the status of practicing professional and of his beneficiaries; And
- the description of his activity consisting solely in the exercise of the legal profession.
(5) A legal entity under Luxembourg law or foreign law practicing the profession of lawyer cannot be or remain registered on list V of the table of the Order of its headquarters if it does not include one or more partners registered on the list I of the table of the Order practicing their profession permanently in Luxembourg who exercise a significant influence on the activity of the legal entity in Luxembourg. A legal entity under Luxembourg law or foreign law practicing the profession of lawyer cannot be or remain registered on list VI of the table of the Order of its headquarters if it does not include at least one partner registered on list I or in list IV of the table of the Order who practices his profession permanently in Luxembourg.
(6) The members of the management bodies of a legal entity practicing the legal profession must be partners of the legal entity. [...]” (Law of August 10, 1991 on the profession of lawyer, Mém. A58 of 08/27/1991, as amended by Law of 20 July 2021, Articles 5, 6 and 34 [google translation])
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previously up to 2021
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"Artcile 2
(1) Lawyers alone can assist or represent the parties, apply and plead for them before courts of any kind, receive their documents and titles in order to present them to the judges, carry out and sign the acts necessary for the regularity of the procedure and put the case ready to receive judgment.
The provisions of paragraph (1) do not prevent the faculty
- socially insured persons to be assisted or represented by a delegate of their professional or trade union organization before the Arbitration Council or the Superior Council of Social Insurance,
- litigants to be represented or assisted by a chartered accountant or a company auditor, duly authorized to practice their profession, before the courts sitting in matters of direct contributions,
- of the public prosecutor to represent parties in court in the cases provided for by law.
(2) No one may, directly or through an intermediary, give, on a regular basis and for remuneration, legal consultations, or draw up documents under private signature for others, if he is not authorized, under the terms of this law, to practice the legal profession.
[...]
Art. 5.
No one may practice the profession of lawyer if he has not obtained registration on the roll of a Bar Association established in the Grand Duchy of Luxembourg.
Art. 6.
(1) Pour être inscrit au tableau, il faut:
a)	présenter la garantie nécessaire d'honorabilité.
b)	justifier de l'accomplissement des conditions d'admission au stage. Exceptionnellement, le Conseil de l'ordre peut dispenser les personnes ayant accompli leur stage professionnel dans leur Etat d'origine et pouvant attester d'une pratique professionnelle d'au moins cinq ans, de certaines conditions d'admission au stage.
c)	être de nationalité luxembourgeoise ou être ressortissant d'un Etat membre des Communautés Européennes. Le Conseil de l'ordre,après avoir pris l'avis du ministre de la Justice, peut, sur la preuve de la réciprocité de la part du pays non-membre de la Communauté Européenne dont le candidat est ressortissant, dispenser de cette condition. Il en est de même des candidats qui ont le statut de réfugié politique et qui bénéficient du droit d'asile au Grand-Duché de Luxembourg.
(2) Avant d'être inscrits au tableau des avocats, les candidats-avocats,sur présentation par le Bâtonnier de l'Ordre ou de son délégué, prêtent devant la Cour de cassation le serment en ces termes «Je jure fidélité au Grand-Duc, obéissance à la Constitution et aux lois de l'Etat; de ne pas m'écarter du respect dû aux tribunaux; de ne conseiller ou défendre aucune cause que je ne croirais pas juste en mon âme et conscience».
[...]
Art. 34.
(1) Lawyers may associate with one another and decide on the legal form and terms of their association, its representation with regard to third parties, and the rights and duties of partners. All partners must be registered with the Orders provided for by this law or with a Bar Association or other organization representing the professional authority of a Member State of the European Communities.
(2) The Bar Council may, by way of derogation from the foregoing, allow the association with lawyers registered with a Bar Association or with another organization representing the professional authority of lawyers of a State which is not a member of the European Communities. the condition of noting that this order or association ensures, in addition to reciprocity, conditions of registration, exercise of the profession and association equivalent to those provided for by this law.[...]" (Law of August 10, 1991 on the profession of lawyer, Mém. A58 of 08/27/1991, Articles 5, 6 and 34 [google translation])
Law of August 10, 1991 on the profession of lawyer, Mém. A58 of 08/27/1991, as amended by Law of 20 July 2021;
Law of August 10, 1991 on the profession of lawyer, Mém. A58 of 08/27/1991
[<a href="https://legilux.public.lu/eli/etat/leg/loi/1991/08/10/n3/consolide/20210822">Law</a>],[<a href="https://legilux.public.lu/eli/etat/leg/loi/1991/08/10/n3/jo">Law</a>]