Short answer. Generally no. Section 5 of Rule 64 says findings of fact of the Commission supported by substantial evidence shall be final and non-reviewable. A Rule 64 petition is meant to review legal questions the Commission's factual findings do not settle, not to relitigate facts the Commission already found on substantial evidence.
What the law says
Findings of fact of the Commission supported by substantial evidence shall be final and non-reviewable.
Rule 64, Section 5 — Form and contents of petition. Read the full provision →
What the law says
The petition shall state the facts with certainty, present clearly the issues involved, set forth the grounds and brief arguments relied upon for review, and pray for judgment annulling or modifying the questioned judgment, final order or resolution.
Rule 64, Section 5 — Form and contents of petition. Read the full provision →
The finality rule stated directly
Section 5 answers your question in a single, unqualified sentence: Findings of fact of the Commission supported by substantial evidence shall be final and non-reviewable. As long as the Commission's factual findings rest on substantial evidence, the rule treats them as settled rather than as something a Rule 64 petition can reopen and argue afresh, whether the Commission is COMELEC or COA.
What the petition is actually built to contain
Section 5 describes what the petition itself must present: The petition shall state the facts with certainty, present clearly the issues involved, set forth the grounds and brief arguments relied upon for review, and pray for judgment annulling or modifying the questioned judgment, final order or resolution. The petition works with the facts and issues as they stand, arguing grounds for annulling or modifying the ruling, rather than functioning as a venue to re-try the underlying facts from scratch as if no findings had ever been made.
Why 'supported by substantial evidence' is the qualifier that matters
The finality Section 5 grants is not unconditional — it is tied to the Commission's findings actually being supported by substantial evidence. That phrase is the hinge: a factual finding resting on substantial evidence is put beyond review, while the substantiality of the evidence behind a given finding remains a fair subject to test in the petition itself, rather than the finding's correctness on the merits.
What this means for challenging a COMELEC or COA ruling
Because factual findings resting on substantial evidence are shielded from review, a Rule 64 petition is generally the wrong vehicle for arguing that the Commission simply got the facts wrong when the evidence supporting those facts was substantial. The petition is built around grounds and arguments for annulling or modifying the ruling, which points the challenge toward legal error rather than toward re-arguing settled facts, and toward whether the evidence behind a finding truly rose to the substantial-evidence standard in the first place.