EXPLAINER: Can a person facing a case still testify as a witness in legal proceedings?

During the impeachment trial of Vice President Sara Duterte, Senator-judge Robin Padilla had asked the prosecution to avoid presenting witnesses who were facing charges.

But is having a case grounds to bar someone from being a witness?

Lead prosecutor Rep. Gerville Luistro told Padilla that their witnesses, National Bureau of Investigation (NBI) Regional Director Jeremy Lotoc, and NBI senior agent John Mark Calilung, did not have pending cases.

Moreover, Luistro said that having a case or a conviction does not disqualify a person from being a witness.

“A conviction is not grounds for disqualification unless it is final, and unless it is punishable by more than one year and that the crime constitutes moral turpitude,” Luistro said in a mix of English and Filipino.

What do the rules say?

According to Section 21, Rule 130 of the 2019 Rules on Evidence, the "religious or political belief, interest in the outcome of the case, or conviction of a crime, unless otherwise provided by law” is not a ground for the disqualification of a witness.

However, University of the Philippines College of Law Asst. Prof. Paolo Tamase said that even if a person with a prior case or conviction testifies, it could still affect their credibility.

“Prior conviction, prior cases that were filed against you, in general, they do not affect if you are allowed to testify. But it may affect how much trust is given to you as a witness,” Tamasa said in Filipino.

In the Rules on Evidence, Section 12 of Rule 132, the credibility of a witness can be impeached or challenged if there is evidence that they were “convicted by final judgment” in a case where the punishment is more than a year, or if the case has something to do with moral turpitude, no matter what the punishment is.

Tamase said that cases of perjury or lying under oath can be cited to question whether or not a witness is telling the truth. However, it should be reiterated that a person facing a case does not automatically mean that they are guilty. –Jean Mangaluz/NB, GMA News