Under Georgia law, the credibility of a witness is to be determined by the jury. O.C.G.A. § 24-9-80; O.C.G.A. § 24-6-620. The credibility of an alleged victim may not be bolstered by the testimony of another witness. Gaston v. State, A12A0962. Thus, a witness may not give an opinion as to whether the alleged victim is telling the truth. Damerow v. State, 310 Ga. App. 530 (2011); Hopson v. State, 307 Ga.
App. 49 (2010).
A witness, even an expert, can never bolster the credibility of another witness as to whether the witness is telling the truth. Accordingly, "testimony that another witness believes the victim impermissibly bolsters the credibility of the victim." Gregoire v. State, 309 Ga. App. 309 (2011); Mann v. State, 252 Ga. App. 70 (2001) (failure to object to testimony that "I believed him [the victim]" constituted deficient performance).
Normally, a party may not bolster the truthfulness of its own witness until the witness has been impeached by the other side. Miller v. State, 275 Ga. 32 (2002); State v. Braddy, 254 Ga. 366 (1985). After a party's witness has been cross-examined, they can be asked on re-direct examination if they are telling the truth and assert their own credibility by testifying that they are telling the truth. Handley v. State, 289 Ga. 786 (2011); Hardy v. State, 293 Ga. App. 265 (2008); Miller v. State, 275 Ga. 32 (2002).