
Siegler Bird & Bird Ügyvédi Iroda operates one of the largest data protection practices in Hungary, with international clients spanning the automotive, healthcare, banking, and technology sectors. The firm excels in comprehensive GDPR audits, data breach management, and contentious regulatory proceedings before the Hungarian authorities. Its expertise also covers pioneering work in NIS2 compliance, the DSA, and AI development. The practice is co-led by Bálint Halász, who focuses on IT, privacy, and data protection litigation, and Ádám Simon, who handles cross-border cybersecurity compliance, NIS2 strategy, and international data transfers. They are ably supported by Judit Nagy, who is experienced with European data protection and privacy compliance matters.
Legal 500 Editorial commentary
Accolades
Client satisfaction: Lawyer & team quality
Client satisfaction: Billing & efficiency
Client satisfaction: NPS ®
Testimonials
Collated independently by Legal 500 research team.
- Their professionalism, responsiveness, and client-focused approach make working with them an incredibly positive experience. I can always rely on their expertise across a wide range of topics, and I consistently feel confident that their support is the best. I always feel well-supported and valued as a client.
- They always answer my calls promptly and provide timely, well-considered responses. They fully understand the core of complex legal issues and never give vague or general answers.
- ‘The team is very strong in data protection, they really understood the assignment quickly and got right to the point. They’re extremely responsive and pragmatic, and they’re just easy to deal with and more on top of the details.’
- ‘Ádám Simon stood out for his strategic view and ability to simplify complex issues, and for being so reliable and sharp on details.’
- ‘The team had clean, transparent, and traceable communication with us through the entire project, from offer to completion. Their tone was courteous and collaborative at all times, regardless of which of our employees they were speaking with. We received all project-related documents in impeccable condition and form, and in a timely manner (well ahead of any decision deadline).'
- 'The project was consistently predictable, as we always knew how it should unfold, what still lay ahead of us, what the next steps were, and when and who would contact us. When reaching out to us, they correctly addressed our designated employees by topic; there was no misdirection, error, or confusion in the communication.’
Key clients
- Bitrise
- Yettel
- Viber
Work highlights
Assisted one of Hungary's fastest-growing tech startups, Bitrise, with all types of privacy compliance topics.
Supported one of Hungary's largest mobile network operators, Yettel, with a range of complicated data protection issues.
Represented the leading cross-platform messaging application developer, Viber, successfully in the competition control proceedings of the GVH (Hungarian Competition Authority) for the alleged infringement of unfair business-to-consumer commercial practices in relation to the processing of personal data.
Lawyers
Next Generation Partners
Junior partners with significant recognition from clients and peers in the market and key roles on multiple matters.

Leading associates
Leading associates with regular involvement in their team's key work, and recognition from peers or clients as being ones to watch.
Practice head
Bálint Halász; Ádám Simon
Other key lawyers
Judit Nagy

