Constitutional Charter (Articles 2, 3 and 32)
The constitutional principle of equality states that «All citizens have equal social dignity and are equal before the law, without distinction of sex, race, language, religion, political opinion, personal or social condition.» (art. 3, paragraph 1, Constitution). This principle does not expressly mention gender identity  or the transgender condition, which is understandable if we consider that the Constitutional Charter was drafted in the 1940s, when there was no awareness about the subject. However, there can be no doubt about the ‘strength’ of the principle of equality and of the Constitution as a whole, as instruments to protect the transgender person. This is primarily in the name of the ‘personalist principle’ that places the person, his or her needs, rights and freedoms at the center of the ‘constitutional project’. «The Republic recognizes and guarantees the inviolable rights of the person, both as an individual and in the social groups where his/her personality is expressed. The Republic expects that the fundamental duties of political, economic and social solidarity be fulfilled.» (art. 2). This means, in fact, that the Italian Constitution gives centrality to the person regardless of any personal condition. Moreover, the same principle of equality does not itemize the protected conditions in a peremptory and exclusive manner, so much so, as to close with an expression —‘personal or social conditions’— which can be understood to protect any personal characteristic. Article 3 assigns to the Republic the task of «removing any obstacle of an economic or social nature which constrains the freedom and equality of citizens, thereby impeding the full development of the human person and the effective participation of all workers in the political, economic and social organization of the country.» (art. 3, paragraph 2), which can certainly be invoked to protect the transgender person. Article 32 protects health as a fundamental right of every citizen, and establishes that no one can be made to undergo a specific health treatment if not by legal obligation.

Law no. 164 of April 14, 1982, «Rules Concerning the Rectification of Sex-Attribution»
Law No. 164 of April 14, 1982, dictates the provisions on anatomical and legal changes in sex attribution. (Amended in 2011, as part of the reform of the rules of civil procedure, by Legislative Decree No. 150 of September 1, 2011, «Additional provisions to the Code of Civil Procedure concerning the reduction and simplification of civil procedures in matters of cognition», in particular, see art. 31, «Of disputes in matters of rectification of sex attribution», amended in turn  by the implementing decrees of the Cirinnà Law, i.e., Legislative Decree no. 5 of January 19, 2017, «Adaptation of the provisions of the civil status system regarding registrations, transcriptions and annotations, as well as regulatory amendments and additions for the regulation of civil unions»).
This law passed with the primary goal of “regularizing” the registry issues of those people who had undergone surgery abroad but were not recognized in their new identity in Italy, and to allow access to free-of-charge surgery within the public health system. This would explain the rather hasty manner in which this law deals with certain issues. Although it was very innovative at the time –for it allows the variation of sex characteristics and gender markers-- today it appears to be insufficient and in need of updates so as to respond to the continuous rise of new demands. Over the years, questions have been raised about some phrasings that are not entirely clear. For example, the law establishes that a court order is necessary for surgery «when it is necessary to change sex characteristics through medical-surgical treatment», seeming to admit that surgery is just a possible step (Art. 31, paragraph 4, Legislative Decree 150/2011). It also does not clarify what is meant by “medical-surgical treatment”, i.e., whether hormone therapy and modification of secondary sex characteristics is considered sufficient. If until 2015, judges mostly understood that sex reassignment surgery was necessary, they have later admitted that it is a non-necessary condition, also in consideration of two rulings: 221/2015 of the Constitutional Court and 15138/2015 of the Court of Cassation.

Legislative Decree no. 198 of April 11, 2006, «Equal Opportunities Code of Practice for Equality and Diversity between men and women»
Although this is a legislative text aimed at combating discrimination between men and women, it should certainly be interpreted, in accordance with European Union law (see the section “The protections of European Union law”), as also protecting people who are discriminated against due to gender reassignment or because of gender identity in general. This is the only reference to anti-discrimination protections because there is no clear regulation, as there is for sexual orientation (Legislative Decree no. 216/2003) and other personal conditions, instead.

Law no. 76 of May 20, 2016, «Regulations on civil unions between persons of the same sex, and rules of cohabitation», so-called “Cirinnà Law”, art. 1, paragraphs 26 and 27
«26. The court order granting legal gender recognition determines the dissolution of the civil union between persons of the same sex.»
«27. On the date of legal name change and gender marker update, where the spouses have expressed their willingness not to dissolve the marriage or cease its civil effects, there follows the automatic establishment of a civil union between persons of the same sex.»
The so-called “Cirinnà law” provides that upon legal name change and gender marker update, there will be the dissolution of the civil union, while in the case of a matrimonial bond, the marriage will be turned into a civil union.

Law n. 354 of July 26, 1975, «Provisions on Penitentiary Regulations  and on the Implementation of Measures Depriving and Restrictive of Freedom.», so-called Penitentiary Regulations, specifically art. 1
«Art. 1, Treatment and re-education: 1. Penitentiary treatment must conform to standards of humanity and ensure respect for the person’s dignity. It is marked by absolute impartiality, without discrimination on grounds of sex, gender identity, sexual orientation, race, nationality, economic and social conditions, political opinions and religious beliefs, and conforms to models that promote autonomy, responsibility, socialization and integration.»
This is a recently amended (2018) and very innovative piece of legislation that expressly mentions gender identity as a condition that may not generate discrimination in detention.

Legislative Decree n. 251 of November 19, 2007, «Implementation of Council Directive 2004/83/EC on minimum standards for the qualification and status of third country nationals or stateless persons as refugees or as persons who otherwise need international protection, and the content of the protection granted»
This decree considers the transsexual condition as a possible reason for requesting, and be granted, a residence permit for humanitarian reasons.
Art. 8, «Reasons for persecution», «1. In order for refugee status to be granted, the acts of persecution referred to in Article 7 or the lack of protection against such acts must be attributable to the reasons defined below: ... (d) «a particular social group» is one consisting of members who share an innate characteristic or common background that cannot be changed, or share a characteristic or belief that is so fundamental to identity or conscience that a person should not be forced to renounce it, or rather that group has a distinct identity in the relevant country, because it is perceived as being different from the surrounding society. Depending on the circumstances in its country of origin, a particular social group may be identified because of the common characteristic of sexual orientation, provided that such orientation does not entail acts that are punishable by Italian law. For the purpose of determining membership in a particular social group or identifying the characteristics of that group, due consideration shall be taken of gender factors, including gender identity».

Charter of Fundamental Rights of the European Union, so-called Nice Charter (2000)
Articles 1, 2 and 3 of the Charter of Fundamental Rights of the European Union guarantee the right to the human dignity, life and integrity of the person.
Articles 6, 7, and 8 guarantee the right to liberty and security, respect for private and family life, and protection of personal data.
Article 14 acknowledges the right to education.
Article 20 (Equality before the law): «Everyone is equal before the law».
Article 21 (Non-discrimination): 1. «Any discrimination based on any ground such as sex, race, color, ethnic or social origin, genetic features, language, religion or belief, political or any other opinion, membership of a national minority, property, birth, disability, age or sexual orientation shall be prohibited.»
Article 35 recognizes the right to health protection.

Treaty on the Functioning of the European Union (2007)
Article 10: «In defining and implementing its policies and activities, the Union shall aim to combat discrimination based on sex, racial or ethnic origin, religion or belief, disability, age or sexual orientation.»
Article 19 (ex Article 13 TEC): «1. Without prejudice to the other provisions of the Treaties and within the limits of the powers conferred by them upon the Union, the Council, acting unanimously in accordance with a special legislative procedure, and after obtaining the consent of the European Parliament, may take appropriate action to combat discrimination based on sex, racial or ethnic origin, religion or belief, disability, age or sexual orientation.»

Directive 2006/54/EC of the European Parliament and of the Council, of 5 July 2006 «on the implementation of the principle of equal opportunities and equal treatment of men and women in matters of employment and occupation (recast)». 
«The Court of Justice has held that the scope of the principle of equal treatment for men and women may not be confined to the prohibition of discrimination based on the fact that a person is of one or other sex. Considering its purpose and the nature of the rights which it seeks to safeguard, it also applies to discrimination arising from the gender reassignment of a person.» (Directive 2006/54/EC; Recital 3). This act has been transposed into the so-called Equal Treatment Code, i.e., the reference legislation for preventing discrimination between men and women (see above). Although it does not expressly refer to the transgender condition, it is a basal text because it has taken up the indications of the Court of Justice that, in some pronouncements, recognized that the protections against discrimination between men and women (i.e., the protections then established by Directives 76/207 and 2002/73, then consolidated by Directive 2006/54) also extended to those who were discriminated against because of gender reassignment, (C-13/94, S. and Cornwall County Council [1996]; C-117/01, K.B. v. National Health Service Pensions Agency, Secretary of State for Health [2004]; C-423/04, Richards v. Secretary of State for Work and Pensions [2006]). Taking its cue from these decisions, the European Union has thus declared that the principle of equal treatment between men and women cannot be limited to the prohibition of discrimination based on the fact that a person belongs to one sex or the other, but must also apply to discrimination resulting from gender reassignment (Directive 2006/54/EC; Recital 3). 
Although it can be criticized for many reasons -for example because it is contained in a part of the Directive that is not binding for the Member States since it would confine the protection to those who have carried out gender reassignment, but not to those who would like to do so or are doing so (“discrimination arising from gender reassignment”), and also because it seems to take for granted that there are two sexes and that a person can only change from one to the other (“the fact that a person is of one or other sex”), this provision is of certain importance. In fact, its formulation determines an extension of the protections regarding discrimination on the grounds of sex or gender against transgender people, as judges have started recognizing in Italy, which is certainly a fundamental aspect since gender identity is not expressly protected by EU law.

Convention for the Protection of Human Rights and Fundamental Freedoms, so-called ECHR (1950) Article 14, «Prohibition of Discrimination».
«The enjoyment of the rights and freedoms set forth in this Convention shall be secured without discrimination on any ground such as sex, race, color, language, religion, political or other opinion, national or social origin, association with a national minority, property, birth or other status.» The framework of protections also refers to the instruments of international law.

Some Regions have used the leeway offered by the division of State-Region competencies, and introduced laws against discrimination on grounds of gender identity.
Tuscany Regional Law n.63 of 15.11.2004, «Norms against discrimination on grounds of sexual orientation or gender identity».
Liguria Regional Law n.52 of 10.11.2009, «Norms against discrimination on grounds of sexual orientation or gender identity»
Marche Regional Law n.8 of 11.02.2010, «Provisions against discrimination on grounds of sexual orientation or gender identity».
Piedmont Regional Law n.5 of 23.3.2016, «Norms for implementing the prohibition of any form of discrimination, and equal treatment in matters of regional competence»
Decree of the President of the Piedmont Regional Council n. 6/R of 27.2.2017. Regional Regulation on «Implementation of Regional Law n.5 of 23 March 2016 (Norms for implementing the prohibition of any form of discrimination, and equal treatment in matters of regional competence)»
Umbria Regional Law n.3 of 11.4.2017, «Norms against discrimination and violence on grounds of sexual orientation and gender identity»
Emilia Romagna Regional Law n.15 of 1.8.2019, «Regional law against discrimination and violence on grounds of sexual orientation or gender identity»
Campania Regional Law n.37 of 7.8.2020, «Norms against violence and discrimination on grounds of sexual orientation or gender identity, and amendments to the regional law n. 14 of February 16, 1977 (Establishment of the Regional Women's Council)»
Resolution of the Tuscany Regional Council n.329 of 29.03.2021, «Agreement between the Region of Tuscany and Public Administrations of the Tuscany Region adhering to the RE.A.DY Network for the promotion of the network, to strengthen the collaboration between local Public Administrations and the integration of related policies at the regional level».