There are no laws on dating, legal issues only become part of the picture if you're going to have sex, in which case laws vary from state to state on that. However, the operative words in your question are "without parental consent". A 16 year old is still a minor, and by law, a minor's parents/guardians have every right to control who can and cannot have contact with their child, until the child is of legal age. So, yes a 16 y/o can date a 23 y/o AS LONG as the 16 y/o's parents approve. However, if the parents do not approve of the relationship, they are entitled to insist the person stay away from their child. If the person was to persist in seeing the 16 y/o against the parents' wishes, the parents could legally have the person charged with harassment and seek a restraining order against the person if necessary.