In the majority of rapes on college campuses, both parties involved had been drinking - often to excess. Alcohol lowers inhibitions and can often heighten the desire for sexual activity. Those who expect sex after they have been drinking may use force if they encounter resistance. Fifty-five percent of the college men who acknowledged committing sexual assault on a date reported being under the influence of alcohol at the time of the assault.
Communication also suffers when alcohol is involved.
It is hard enough to communicate about sex when sober. Trying to communicate and make good decisions when drinking is impossible for most people.