There is no difficulty with your cctv covering a public area but it should not intrude on someone else's private property. If you have dashcam footage of an incident, there are no DP issues unless you publish the footage without consent of persons featured therein. Garda can 'request' footage or they can subpoena footage. One is voluntary, the other compulsory. The request should be in line with S.47 of the DP Act, 2018. Part 5 of the 2018 Act is the Law Enforcement Directive which gives law enforcement authorities, such as local authorities and police forces, considerable powers in relation to the processing of personal data as well as imposing obligations, similar to the GDPR.