"Because if you have a law that will criminalize this particular age group, then the criminals will not use them," Panelo said.
He quoted reports from the Philippine National Police and the Filipino drug trafficking gangs using children under 15 in their operations. But Mr Dongeto said that state statistics showed that less than 2 percent of all crimes were committed by children.
On Monday, the police said from January 2017 to December 2018 that more than 1,300 minors had been arrested for illicit drugs. They were mostly used as "runners" or mules because criminals know that children cannot be prosecuted under current laws, police said.
"An iron snake is not the solution. Jailing our children and mistreatment are not solutions," said Mr. Pangilinan, who promised to block the proposed changes to the Senate. "Go for big villains and reform 9-year-olds."
Senator Grace Poe, who has opposed previous attempts to lower the age of criminal prosecution, agrees.
"By lowering the age of crime to 9, we want to create kindergarten prisons, and instead of rehabilitating children, these finished schools for young criminals, their impressive minds are taught by the best in trade," she said in a declaration.