Metro Manila (CNN Philippines) — Thirty years ago, they helped draft a new constitution for the country, following the 1986 revolution that deposed the Marcos regime and restored democracy.

Now, on Constitution Day, framers of the 1987 Constitution are opposing planned ammendments to the charter.

Former constitutional commissioners Christian Monsod, Hilario Davide, Jr., and Edmund Garcia are particularly opposing a shift to a federal form of government.

Lawyer Christian Monsod says the Constitution is not the problem, but rather the failure of government to fully implement it.

"A messed-up shift to a federal constitution is virtually irreversible. And will consume the energies of the government for other priorities that demand its attention," Monsod said during an event commemorating the 30th anniversary of the ratificiation of the 1987 Constitution.

Under federalism, the country will be divided into autonomous regions or states.

Watch: How ready is Congress to amend the Constitution?

Duterte believes this is the only way to solve the problem in Mindanao. In December, he asked House Speaker Pantaleon Alvarez to speed up efforts for charter change leading to federalism.

Former Chief Justice Hilario Davide, however, says the 1987 Constitution already provides a framework for addressing challenges Filipinos face as a people.

He says this is the best Constitution in the world — describing the charter as pro-God, pro-poor, and pro-people.

The former chief justice said he is prepared to do what is necessary to protect the Constitution he helped frame three decades ago.

"I would be willing to die against any move to amend this Constitution," Davide declared.

Author Edmund Garcia, a human rights and peace advocate, and political scientist, says amending the Constitution might just magnify current problems rather than solve them.

"Once you open the Constitution to amendments or changes, then they can touch any other provision. Like the provisions on the limitations to the declaration of Martial Law, thats an example," Garcia explained.

At the heart of the 1987 Constitution, they say, is social justice and human rights.

They believe it is most crucial to protect the constitution today, when human rights are under threat--referring to the spate of killings associated with the government's drug war.

Also read: Lawmakers take federalism course before convening for cha-cha