Opening a Chartered Accountant's office during a lockdown, when it's not deemed an essential service, can lead to legal trouble. Authorities might file cases under Section 144 of the Cr.P.C. read with Section 188 of the IPC for violating lockdown orders. Proof can be gathered through video footage showing the date and time. The specific sections invoked will depend on the exact laws violated during the enforcement of the lockdown.