Romkeslaan 59
8933 AR Leeuwarden
T +31 20 236 10 24
F +31 20 796 92 22

Jan van Goyenkade 10 III
1075 HP Amsterdam
T +31 20 737 20 66
F +31 20 796 92 22


ENVIR Advocaten is the specialist in the fields of administrative law and environmental law.

Marieke Kaajan

mr. drs. M.M. (Marieke) Kaajan

Marieke Kaajan is a partner and one of the founders of ENVIR Advocaten. She specialises in administrative law, with a focus on environmental law and nature conservation law.

As a lawyer, Marieke takes a highly practical approach. Also thanks to her experience with complex projects and knowledge of government processes, she can adapt easily to changing circumstances and quickly determines which approach will make the case truly move along. Marieke worked at Stibbe as a lawyer for 13 years in the administrative law and environmental law department.
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Fleur Onrust

mr. drs. F. (Fleur) Onrust

Fleur Onrust is a partner and one of the founders of ENVIR Advocaten. Fleur Onrust worked as an administrative law lawyer at Stibbe for 10 years. Fleur specialises in environmental law, focusing primarily on species protection under the Nature Conservation Act (formerly the Flora and Fauna Act), the Environmental Permitting (General Provisions) Act and administrative spatial planning and zoning law.

In addition, Fleur is often involved in general administrative law, in particular subsidy regulations, enforcement issues and administrative procedural law. In addition, she is also active as an attorney in (public) healthcare, education and culture, where she deals with questions and procedures related to subsidies, permits or other types of government regulation.
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Iris Kieft

mr. I.F. (Iris) Kieft

Iris Kieft is a partner of ENVIR Advocaten who advises companies, developers and government bodies on planning and environmental aspects of development projects, consenting and transactions. Iris has a particular focus on planning and (environmental) consenting in the Dutch energy & infrastructure and real estate sectors. Her practice also includes climate change and sustainable development.

As an attorney, Iris is creative and committed. She enjoys supporting her clients in successfully navigating complex legal and environmental challenges. Iris worked for 9 years in the administrative law department and energy sector group of De Brauw Blackstone Westbroek. Prior to joining ENVIR Advocaten in 2018, Iris worked in the Real Estate & Construction department and energy sector group of CMS Netherlands.
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Erwin Noordover

mr. E. (Erwin) Noordover

Erwin Noordover is a partner of ENVIR Advocaten. He is specialized in general and European administrative law, with a focus on environmental, planning and nature conservation law.

Erwin advises and litigates on behalf of both government bodies and developers on (sustainable) energy and nature conservation issues relating to wind and solar farms, energy transition, and scarce rights or subsidies for sustainable energy production. Erwin is practical and solution-oriented, with a keen eye for potential opportunities and risks and the best stage of a project to address these. Before Erwin became a partner at ENVIR Advocaten, he worked for more than 10 years as a lawyer at Stibbe in the administrative and environmental law section.
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Derek Sietses Home

mr. D. (Derek) Sietses

Derek Sietses is a partner of ENVIR Advocaten. Derek’s expertise covers administrative law, including environmental law, EHS matters and nature conservation law, as well as civil law, including contracts liability matters.

Derek has extensive experience in complex, politically sensitive cases, both representing local authorities, including municipalities, provinces and enforcement agencies, and companies and developers. Derek is practical and efficient and brings a strategic and commercial approach to the table when assisting his clients. He is therefore well-placed to help his clients successfully navigate the complex legal context in which they operate.
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