He was again charged under the Sedition Act in March 2009 with threatening to sue the Sultan of Perak, Sultan Azlan Shah, in the wake of the 2009 Perak constitutional crisis. Karpal had contended that the sultan had exceeded his constitutional powers in appointing Zambry Abdul Kadir Menteri Besar. The charges were dismissed in June 2010 after the High Court determined that the prosecution had failed to prove a prima facie case. However, the Court of Appeal reversed the acquittal in January 2012 and ordered Karpal to enter a defence. In March 2019, 10 years after the incident the Federal Court acquitted Karpal posthumously.
