Rainer Frank advises and represents companies and organizations in the private and public sector in all cases relating to criminal law, administrative offences law and criminal compliance. This includes the defense of employees as well as counseling and representing companies that became victims of criminal offenses or that suspect legal violations within their own company. His clients include companies from a wide range of industries - from SMEs to DAX 30 corporations - as well as public authorities and institutions.

In his defense work, he particularly focuses on cases involving white-collar criminal law, including labor criminal law, environmental protection and occupational safety criminal law.

Rainer Frank has extensive knowledge and experience in the area of Compliance. About thirty companies and organizations in the private and public sector have appointed him as a legal ombudsman / lawyer of confidence and entrust him with receiving confidential information on legal violations.

Rainer Frank has been a certified Compliance Auditor (TÜV) since 2017 and a certified Compliance Officer (Steinbeis) since 2020. Additionally, he serves as external compliance officer for companies and organizations.

From 2013 to 2018, Rainer Frank has led the Whistleblower Working Group at Transparency International Deutschland e.V.