Lennard has worked as a patent attorney since 2015 and joined Brann in 2022. He began his patent career at the Dutch intellectual property firm Arnold & Siedsma, where he was part of the firm's Electronics and Software group.

His technical expertise covers electronics, software and materials science, with a particular focus on catalytic surfaces and energy-storage materials. This expertise is underpinned by a strong scientific background: Lennard obtained his Ph.D. in engineering physics from Delft University of Technology (TU Delft) in 2013, has around ten scientific publications, and subsequently spent two years as a postdoctoral researcher at the Department of Physics and Astronomy at Uppsala University.

For his clients, Lennard works across the full patent lifecycle - novelty searches, drafting applications, prosecution before patent offices, freedom-to-operate analyses, oppositions and disputes. He is authorised as both a Dutch Patent Attorney and a European Patent Attorney and is also entitled to represent parties before the Unified Patent Court (UPC) as a UPC Representative. Lennard works in English, Dutch and Swedish.