The President may call a special session at any time. (Art. VI, Sec. 15, 1987 Constitution)
● Power to call special session is vested in the President, not in the
Senate President or the Speaker of the House.
Instances when the
Congress may meet in a special session even without a call from the president:
1. Within 24 hours following the proclamation of martial law or
suspension of the writ of habeas corpus the Congress, if not in session, may
convene without need of a call to:
a. receive President’s report on the proclamation or suspension
b. revoke such proclamation or suspension
c. extend such proclamation or suspension upon the initiative of the
President
"Within 48 hours after
the proclamation of martial law or suspension of the writ of habeas
corpus, the President shall submit a report in person or in writing to the
Congress. The Congress, if not in session, shall, within 24 hours
following such proclamation or suspension, convene in accordance with its rules
without need of a call. The Congress, voting jointly, by a vote of at
least a majority of all its Members in regular or special session, may revoke
such proclamation or suspension, which revocation shall not be set aside by the
President. Upon the initiative of the President, the Congress may, in the same
manner, extend such proclamation or suspension for a period to be determined by
the Congress, if the invasion or rebellion shall persist and public safety
requires it." (Art. VII, Sec 18, 1987
Constitution)
2. In impeachment cases;
3. For the purpose of canvassing the elections of the President or
Vice-President;
4. To enact a law calling for a special election to elect a President
and a Vice-President after the vacancy in such offices occurs.
"The Congress shall, at ten
o'clock in the morning of the third day after the vacancy in the offices of the
President and Vice-President occurs, convene in accordance with its rules
without need of a call and within seven days, enact a law calling for a special
election to elect a President and a Vice-President to be held not earlier than
forty-five days nor later than sixty days from the time of such call. "(Art. VII, Sec. 10, 1987 Constitution)