Total incapacity to work (TIW) is a legal concept that allows magistrates to assess the severity of violence against persons. The TIW is the duration of the victims' inability to fulfil their usual activities and is determined by physicians. Professional guidelines from the French National Authority for Health indicate that TIW applies both to physical and psychological problems. The law of 9 July 2010 makes explicit reference to TIW in cases of psychological violence and intimate partner harassment. Prosecutors base criminal penalties on the duration of TIW in cases of assault and battery. Whatever the physician, they should describe the mental state of the victim and identify the signs that may indicate the mental impact of reported assaults. Identifying combinations of symptoms can be useful in deciding whether the duration of TIW should be increased because of the psychic state. In case of stalking, assessment of TIW can allow prosecutors to link the reported facts to a criminal offence. In complex situations, the physician may be unable to assess a duration of TIW and can suggest expert assessment. In all cases, the duration of TIW needs to be based on functional criteria. The extent of harm to the life of relationships results from suffered violence, from the victim's reaction, and from the perception of their family and friends. In this area, we suggest to limit the first assessment of TIW to a few days and to reassess it later, according to real information reported by the victims, to careful observation of their behaviour, and to results of a questioning that should be as little suggestive as possible. At either end of the age scale and in case of preexisting functional impairment, assessment of TIW should take into account the actual and global capacity of the person before the assault.