This is due to their immunity from suit. This is one reason why graft and corrupt practices in the Philippine government are still rampant. This law is in fact not applicable to the Philippines. So let's not follow USA laws because their politicians are different from our politicians.
I am deeply saddened and disappointed by Mr. Pacquiao's public support for Mr. Singson who recently was reported to have beaten his common-law wife. It is quite embarassing to see a person who represent the Philippines to say that what Mr. Singson has done is justified.