The UK Information Commissioner’s Office has warned that many media companies are breaking the law and urged them to review how they use personal data as it resumed its adtech investigation. Its probe into the UK’s £13bn a year online advertising industry will particularly look into widespread non-compliance with GDPR, the EU data regulations which were incorporated into UK law in 2018. Under GDPR people must unambiguously opt-in to receive marketing communications and to share their personal data. GDPR states that marketers and publishers must also abide by strict rules around the storage of data and how it is shared with other companies.