He has also attended specialized seminars at the Theodor Heuss Academy for Freedom in Gummersbach, Germany and with the Center for Democratic Initiatives at the Australian National University in Canberra, Australia.

In the wake of the assassination of Senator Ninoy Aquino on 21 August 1983, he helped mobilize protest actions in schools demanding justice and radical political change.

He was in the Official Delegation for the 2012 Universal Periodic Review at the Human Rights Council in Geneva that was led by then-Justice Secretary and former CHR Chair Leila De Lima.

He has been involved in many different civil society political alliances working for human rights and democracy such as the Kongreso ng Mamamayang Pilipino (KOMPIL 1 & 2), Bansang Nagkaisa sa Diwa at Layunin (BANDILA), the Black & White Movement, Social Liberals & Democrats for the Advancement of Reforms (SoLiDAR), and Re:Publika@DemokraXXIa - a new network of progressive activists.

He was previously the executive director to both the liberal think tank National Institute for Policy Studies (NIPS) from 1987 to 2002 and LIBERTAS - a lawyers' network on the Rule of Law from 2005 to 2008.

[citation needed] In the transition to democracy, during the term of President Corazon C. Aquino, Gascon served as the youngest member of the 1986 Constitutional Commission that drafted the 1987 Constitution and the 8th Philippine Congress, passing legislation that institutionalized youth participation in local government (Sangguniang Kabataan) as well as a special law providing for special protection of children from all forms of abuse (RA 7610).

He has held several senior positions in government, such as separate stints as Undersecretary at the Department of Education (DepEd, from 2002 to 2005) & the Office of the President (Political Affairs, from 2011 to 2014).