Sexual assault can be difficult to prove. There are no guarantees of winning a civil lawsuit. There are usually no witnesses. The alleged offender may claim that the survivor actually consented to the sexual assault, deny that the abuse occurred, blame the survivor, or rationalize their own conduct. These factors often compound the anxiety of going to court and telling the world what happened.
Before having a survivor of sexual assault go through this process, a lawyer will first decide if there is a realistic chance of winning the case. The lawyer must be able to prove on a balance of probability (i.e., more likely yes than no) that the assault occurred and that damage was suffered. There is no true consent if it is obtained by threats, intimidation, or through breach of trust.
Evidence is an important part of winning a case. Although there may be no eyewitness proof of a sexual assault, there can be other corroborating evidence. Perhaps the survivor told a friend, family member or health care professional of the assaults. In some instances, there may be evidence in the form of letters or diaries that the survivor kept during the abuse. The alleged offender may have a history of abuse, relevant medical or psychological history, or a tendency to violence. If the offender has been criminally convicted, this will help the survivor's case.
In reality the vast majority of civil cases do not end up in a trial. Rather they are settled out of court. The amount of the settlement depends on the strength of the case and the damages which the survivor has suffered.