carnal knowledge against the order of nature

The appellant was convicted of having carnal knowledge of a person against the order of nature (i.e., homosexual sex acts, in this case anal sexual intercourse) in violation of section 145 of the Penal Code Act.  On appeal, appellant’s counsel emphasized the State offered no evidence of penetration, that corroboration is necessary in cases of sexual offenses, and the compromised credibility of several material prosecution witnesses, including a complainant.  Four years before the trial when he was 17 or 18, the complainant testified that he went to the Appellant’s home for a party