Klaas specialises in administrative law with a focus on environmental and planning law. He advises on various matters, including area development, nature and environmental protection, and private law in relation to the public sector. He specifically focuses on politically sensitive developments at the intersection of public and private law. Besides his work as a lawyer, Klaas frequently provides training to politicians and activists from minority groups in developing countries.
Prior to working at Houthoff, Klaas was an alderman responsible for spatial planning.