See Something, Say Something Act of 2009 - Amends the Homeland Security Act of 2002 to grant immunity from civil liability to persons who, in good faith and based on an objectively reasonable suspicion, report suspicious activity indicating that an individual may be engaging, or preparing to engage, in a violation of law relating to an act of terrorism.

Grants qualified immunity from civil liability to any authorized official who observes, or receives a report of, such activity and takes reasonable action in good faith to respond, consistent with applicable law in the relevant jurisdiction. Provides that an authorized official not entitled to assert the defense of qualified immunity shall nonetheless be immune from civil immunity if that official takes reasonable action, in good faith, to respond to the reported activity.