Why only 12 are elected every 3 years for the 24-member Senate?

Manila, March 21 -- If you are voting for the first time in this year's mid-term polls, then you may be among those wondering why the country is electing only 12 members of the Senate every three years, but there are actually 24 senators in attendance during the opening of Congress on the fourth Monday of July following the elections.

This is particularly true in the coming May 13 elections and those of the years 1995, 1998, 2001, 2004, 2007, 2010, 2013, and 2016.

The answer is in the 1987 Constitution itself, particularly in the Transitory Provisions or Article XVIII whose Section 1 states:

"The first election of members of the Congress under the Constitution shall be held on the second Monday of May 1987. The first local elections shal...