Amsterdam: +31 20 737 20 66
Leeuwarden: +31 20 236 10 24

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. In particular, Derek assists both government bodies and developers in various wind and solar projects on questions relating to contracting, permitting, civil law aspects and municipal taxes.

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.

Prior to joining ENVIR Advocaten in 2019, Derek worked for Stibbe Amsterdam in the administrative law and litigation department and at Trip Advocaten en Notarissen in Leeuwarden in the administrative law department. Derek regularly publishes in Dutch scientific and professional journals and gives lectures on various legal topics for a wide range of audiences. Derek heads ENVIR Advocaten’s Leeuwarden office.

mr. D. (Derek) Sietses
derek.sietses@envir-advocaten.com
Romkeslaan 59
8933 AR
Leeuwarden

T +31 20 236 10 24

M +31 6 1588 6936

F +31 20 796 92 22

What the team is known for: Respected team covering a broad array of planning and environmental law, with a strong focus on nitrogen emissions legislation and EU regulations concerning nature conservation and habitat protection. Represents clients from the energy and construction sectors, as well as municipalities, in contentious and non-contentious zoning and permitting matters. Also assists clients with soil and groundwater pollution mandates.

Chambers, 2021

Fleur Onrust is experienced in handling environmental permitting matters, as well as nature conservation and soil contamination mandates. She is particularly well respected for representing clients from the private and public sectors in contentious proceedings. One client comments: “She is pragmatic, acts fast and is very understanding of the needs of her clients.”

Chambers, 2021

‘Niche firm, but can handle big cases on environmental law’.

Legal 500 – EMEA 2021

‘Iris Kieft is a very bright lawyer, she’s down to earth and friendly, but at the same time very effective and focused on results’.

Legal 500 – EMEA 2021

‘ENVIR Advocaten is one of the leading law firms in the Netherlands in the field of environmental law’.

Legal 500 – EMEA 2021

‘ENVIR Advocaten has very experienced lawyers, which includes some of the best in the field’.

Legal 500 – EMEA 2021

Another client appreciates the team’s business-focused approach: “What I really like about ENVIR Advocaten is that we know each other and we know how to efficiently spend time.”

Chambers, 2021

Marieke Kaajan advises on contentious and non-contentious permitting and zoning matters. She offers additional experience in nitrogen emissions matters and EU environmental directives. One client enjoys working with her because she is “very well connected, nice, direct and very approachable.”

Chambers, 2021

One client praises the team’s “outstanding knowledge, especially of nature conservation law,” and goes on to add that the team “will not rest until they have achieved their clients’ preferred results.”

Chambers, 2021

‘Its staff consists of very experienced lawyers with a lot of expertise in environmental, planning and administrative law’.

Legal 500 – EMEA 2021