Since 2015, non-EU/EEA nationals can be registered with the Order of Portuguese Engineers and the Order of Portuguese Technical Engineers on the basis of reciprocity. Registration is a prerequisite to practice and to become controlling partners in Engineering firms. 
"Article 3. Degrees in engineering prior to the application of Decree-Law No. 74/2006, of March 24
For the purposes of the provisions of the Statute of the Order of Engineers contained in annex i to this law, namely for the purposes of registration, determination of the internship period, and attribution of professional titles, it is considered that they also satisfy the condition set out in paragraph a) of the paragraph 1 of article 15 of the aforementioned Statute in a specialty in the field of engineering, those who satisfy one of the following conditions:
a) Hold a bachelor's degree in an engineering field awarded by a Portuguese higher education institution within the framework of the study organization prior to the application of Decree-Law no. 74/2006, of March 24, as amended by the Decrees-Laws Nos. 107/2008, of June 25th, 230/2009, of September 14th, and 115/2013, of August 7th;
b) Hold a foreign higher academic degree in a field of engineering that has been granted equivalence to the degree referred to in the previous paragraph, or that has been recognized at the same level.
[...]
ANNEX I (referred to in article 2) [...]
Article 8. Right of establishment
1 - The recognition of professional qualifications of nationals of a member state of the European Union or the European Economic Area obtained outside Portugal for registration as a member of the Order is regulated by Law No. 9/2009, of March 4, as amended by Laws 41/2012, of 28 August, and 25/2014, of 2 May, without prejudice to special conditions of reciprocity if the qualifications in question were obtained outside the European Union or the European Economic Area.
2 - The professional who wishes to register with the Order under the terms of the previous number and who provides services, in a subordinate or autonomous manner or as a member or who acts as a manager or administrator in the Member State of origin, within the scope of an associative organization of professionals, observing the provisions of no. 4 of article 37 of Law no. 2/2013, of 10 January, must identify the organization in question in the request submitted under the terms of article 47 of Law no. 9/2009, of March 4th, amended by Laws no. 41/2012, of August 28th, and 25/2014, of May 2nd.
3 - If the fact to be communicated under the terms of the previous paragraph occurs after the submission of the request for recognition of qualifications, the associative organization in question must be identified before the Order within a maximum period of 60 days.
[...]
Article 11. Engineering societies
1 - Engineers established in the national territory may exercise their profession in groups, forming or joining engineering societies as partners.
2 - The following may also be professional members of engineering societies:
a) Societies of engineers previously constituted and registered as members of the Order;
b) Associative organizations of professionals equivalent to engineers constituted in another Member State of the European Union or the European Economic Area whose capital and voting rights belong mainly to the professionals in question.
3 - The capital requirement referred to in paragraph b) of the previous paragraph is not applicable if the company does not have share capital.
4 - The judgment of equivalence referred to in paragraph b) of paragraph 2 is governed by:
a) Regarding nationals of a member state of the European Union or the European Economic Area, by paragraph 4 of article 1 of Law no. 9/2009, of March 4, amended by Law no. 41/2012 , of August 28th, and 25/2014, of May 2nd;
b) Regarding nationals of third countries whose qualifications were obtained outside Portugal, under the internationally valid reciprocity regime.
5 - Engineering societies enjoy the rights and are subject to the duties applicable to professional members of the Order that are compatible with their nature, with the exception of the right to vote, and are in particular subject to the ethical principles and rules contained in this Statute.
6 - Members of the executive body of professional engineering societies, regardless of their status as members of the Order, must respect the ethical principles and rules, technical and scientific autonomy and the guarantees granted to engineers by law and by this Statute.
7 - Engineering societies may also carry out any other activities that are not incompatible with the activity of engineering, nor in relation to which there is an impediment, under the terms of this Statute, and these activities are not subject to the control of the Order.
8 - The constitution and operation of professional societies is set out in a separate statute.
9 - Without prejudice to the provisions of the previous number, the majority of the share capital with voting rights of engineering companies, if any, belongs to engineers established in national territory, to engineering companies established under national law, or to other forms of an associative organization of similar professionals constituted in another Member State of the European Union or the European Economic Area registered with the Order under the terms of the following article.
Article 12. Associations of professionals from other member states
1 - Associative organizations of professionals equivalent to engineers established in another Member State of the European Union or the European Economic Area for the exercise of professional activity whose manager or administrator is a professional and whose capital with voting rights belongs mainly to the professionals in question and or other associative organizations whose capital and voting rights belong mainly to those professionals may register their respective permanent representations in Portugal, constituted under the terms of commercial law, as members of the Order, being as such equivalent to engineering societies for the purposes of this Statute.
2 - The capital requirements referred to in the previous paragraph are not applicable if the associative organization does not have share capital, applying, instead, the requirement of attributing the majority of voting rights to the professionals referred to there.
3 - The judgment of equality referred to in paragraph 1 is governed by:
a) Regarding nationals of a member state of the European Union or the European Economic Area, by paragraph 4 of article 1 of Law no. 9/2009, of March 4, amended by Law no. 41/2012 , of August 28th, and 25/2014, of May 2nd;
b) Regarding nationals of third countries whose qualifications were obtained outside Portugal, under the internationally valid reciprocity regime.
4 - The legal regime for the registration of professional associations from other member states is set out in the legal regime for the constitution and operation of professional societies that are subject to public professional associations.
Article 13. Third country nationals
1 - Nationals of third countries may register with the Order, for the purpose of exercising the engineering profession on national territory, under agreements under reciprocal conditions.
2 - The candidates mentioned in the previous paragraphs may be required to undertake a professional internship, attend training in ethics and professional deontology and carry out assessment tests, under the terms set out in this Statute and in the regulations approved by the Order for candidates whose qualifications have been obtained in Portugal. 
[...]
Article 29. Collective members
1 - As collective members, legal persons who establish a written agreement with it and who carry out relevant training, research or dissemination of knowledge in an area directly related to engineering can register with the Order.
2 - In the case of associations, it is also necessary, for the purposes of the provisions of the previous paragraph, that at least 50% of their members are registered with the Order. [...]"(Law no. 123/2015 of 2 September, first amendment to the Statute of the Order of Engineers [google translation])
---------------------------
Previously up to 2015
---------------------------
"Article 4. Engineer title
For the purposes of this Statute, an engineer is defined as a holder of a degree, or legal equivalent, in an Engineering course, enrolled in the Order as an effective member, and who is responsible for applying the sciences and techniques relating to the different branches of engineering in activities of research, conception, study, design, manufacture, construction, production, supervision and quality control, including the coordination and management of these activities and others related to them.
Article 5. Nationals of Community States
1 - Nationals of other Member States of the European Community may register with the Order of Engineers, for the purpose of exercising the engineering profession in Portugal, when they hold the academic and professional qualifications legally required for the exercise of this profession in their respective State of origin. .
2 - The competent bodies of the Order may require nationals of Member States of the European Community who have requested, under the terms of the previous paragraph, to register to attend internships or take aptitude tests, in accordance with applicable legislation.
[...]
Article 14. Collective members
1 - Legal persons who establish a written agreement with the Order and who carry out relevant training, research or dissemination of knowledge in an area directly related to engineering may be registered as collective members.
2 - In the case of associations, it is also necessary, for the purposes of the previous paragraph, that at least 50% of their members are registered with the Order. [...]" (Decree-Law no. 119/92 of 30 June that approves the Statute of the Order of Engineers [google translation])
Law no. 123/2015 of 2 September, first amendment to the Statute of the Order of Engineers 
Decree-Law no. 119/92 of 30 June that approves the Statute of the Order of Engineers
[<a href="https://diariodarepublica.pt/dr/detalhe/lei/123-2015-70171988">Law</a>],[<a href="https://diariodarepublica.pt/dr/detalhe/decreto-lei/119-1992-304358">Decree-law</a>]