a.IN AID OF LEGISLATION (sec 21)
President and the SC Justices are NOT compelled to appear.
If summon by Congress under sec 21, cabinet members cannot refuse to appear and can be held in contempt.
The continuance of such incarceration only subsists for the lifetime, or term, of such body. Once the body ceases to exist after its final adjournment, the power to incarcerate ceases to exist as well. Thus, each ‘Congress’ of the House lasts for only 3 years.
In order for a witness to be subject of incarceration, the primary requirement is that the inquiry is within the scopre of Congress powers (i.e. its in AID OF LEGISLATION)
However, cabinet & dept heads and officials lower in rank can refuse to appear on the ground of executive privilege.The following are the officials under executive privilege in aid of legislation (but not in question hour):
(i.) Senior officials of executive departments who in the judgment of the department heads are covered by the executive privilege;
(ii.) Generals and flag officers of the Armed Forces of the Philippines and such other officers who in the judgment of the Chief of Staff are covered by the executive privilege;
(iii.) Philippine National Police (PNP) officers with rank of chief superintendent or higher and such other officers who in the judgment of the Chief of the PNP are covered by the executive privilege;
(iv.) Senior national security officials who in the judgment of the National SecurityAdviser are covered by the executive privilege; and
(v.) Such other officers as may be determined by the President.
Executive privilege covers all confidential or classified information between the President and the public officers covered by EO 464, including :
(i.) Conversations and correspondence between the President and the public official covered by this executive order
(ii.) Military, diplomatic and other national security matters which in the interest of national security should not be divulged
(iii.) Information between inter-government agencies prior to the conclusion of treaties and executive agreements
(iv.) Discussion in close-door Cabinet meetings
(v.) Matters affecting national security and public order
Garcillano cannot invoke executive privilege since he is not a member of the executive, he is a COMELEC commissioner.
The power to punish for contempt is inherent in Congress and this power is sui generis. It cannot be exercised by local government units unless they are expressly authorized to do so.
The problem in this case is when the invited personnel invoke his right against self-incrimination and the most common alibi of "I DON'T KNOW YOUR HONOR"