see - sc.judiciary.gov.ph/jurisprudence/2013/july2013/190340.pdf
"x x x.
"Rogelio admits that he killed Abacco albeit in self-defense. “The rule consistently adhered to in this jurisdiction is that when the accused [admits] that he [is] the author of the death of the victim and his defense [is] anchored on self-defense, it becomes incumbent upon him to prove the justifying circumstance to the satisfaction of the court.”16 With this admission, the burden of evidence is shifted to the appellant to prove that all the essential elements of self-defense are present. He must show and prove by clear and convincing evidence that his act was justified. Otherwise his conviction must be upheld and he cannot be exonerated from criminal liability. On this score, the accused must rely on the strength of his own evidence and not on the weakness of the prosecution’s
evidence.
To successfully invoke the justifying circumstance of self-defense, the following requisites must be present:
(1) unlawful aggression;
(2) reasonable necessity of the means employed to prevent or repel it;
(3) lack of sufficient provocation on the part of the person defending himself.17
Unlawful aggression is the indispensable element of self-defense, for if no unlawful aggression attributed to the victim is established, self-defense is navailing as there is nothing to repel. The unlawful aggression of the victim must put the life and personal safety of the person defending himself in actual peril. A mere threatening or intimidating attitude does not constitute unlawful aggression.18.
x x x."
