Read the first part: On the Constitutionality of the Priority Development Assistance Fund
Pork barrel is, according to Merriam-Webster's dictionary:
"government projects or appropriations yielding rich patronage benefits"
A more technical definition removes the negative connotation and simply means legislative appropriations for specific districts or sectors. The PDAF is pork barrel.
Is patronage intrinsically evil? Is it corruption when a public official served people and those people voted for him afterwards? Is there not a leeway for public officials to make policy on which districts or sectors to prioritize?