It is improper for an attorney to compel a witness to testify that another witness lied when testifying. Appellant was charged with assault to commit murder and other offenses. At trial, he testified that he stabbed the victims in self-defense. His testimony directly contradicted that of the victims and on cross-examination the prosecutor repeatedly asked appellant if the victims were lying and he was telling the truth; to which appellant responded yes. This type of questioning is improper as it elicits testimony regarding the credibility of a witness that is prohibited unless it is admissible as character evidence. But, the court found that because the testimony was not plainly inflammatory, there was no sua sponte duty to exclude it. There otherwise was no error as trial attorney’s failure to object could have been based on reasons of trial strategy, and appellant failed to establish prejudice as the evidence of guilt was overwhelming.