Commentary for Bava Kamma 8:4

A deaf person, an imbecile, or a child encountering them is disadvantageous.

עבד ואשה שחבלו באחרים פטורים – for they lack what to pay.

It is losing proposition to meet up with a deaf-mute, an idiot or a minor: he that injures them is obligated; and they that injure others are exempt.
It is a losing proposition to meet up with a slave or [married] woman; he that injures them is obligated; and they that injure others are exempt. However, they pay after some time; if the woman was divorced or the slave freed they are liable for restitution.
Mishnah four deals with two sets of exceptional categories to personal injury law: the first set includes deaf-mutes, idiots and minors; the second set includes married women and slaves. People who fit into these categories receive payment if someone else injures them and yet do not pay if they injure someone else.
Mishnah five teaches opposite scenarios from those we learned in mishnah three. The law mentioned here reiterates the principle that a person cannot be obligated for the death penalty and a financial penalty for the same crime.
According to our mishnah there are several categories of people who receive payment for injuries done to them but do not pay if they injure others. Section one lists people who according to Jewish law are not capable of taking responsibility for their actions. Therefore if they injure others they are not legally obligated. However, the mishnah points out that this is not a reciprocal law. If one injures them he is still obligated for remuneration. These people, while not halachically capable of being responsible for their own actions, are still human beings and deserve both the protection that the law affords through the right to compensation if injured. One who injures them is obligated, therefore, on all five counts mentioned in mishnah one.
The second category of people who receive payment for injuries done to them but do not pay if they injure others are slaves and women. Slaves and women cannot pay others because their money is linked to their master or to their husband. There is, however, significant difference in this matter between slaves and women. Non-Jewish slaves own no property; everything they acquire belongs to their master. They therefore have no money with which to make financial compensation. In contrast, married women can own property. However, a woman’s husband has a lien on her property and he also has the right to the benefits of the property. For instance if she owns a piece of land, she cannot sell it without her husband’s consent and he gets the benefit of what is grown on the land, as long as they are married. Therefore she doesn’t own any property that is totally available for which to make compensation if she should injure someone else. However, the mishnah teaches that once the slave is freed or the woman divorced or widowed, they now have the obligation to compensate the person they injured.

All this is clear. And there is to the judge to afflict them so as to remove their damages from among people.

נתגרשה האשה ונשתחרר העבד – and they acquired property, they are liable to pay. For at the beginning, they are liable, but they lack what to pay as the usufruct of the wife is mortgaged to her husband for its fruits and for inheritance.