A more thorough explanation:

The legal-unities doctrine is a historical common-law rule that stated that a wife had no separate existence from her husband. This means that a married woman's legal identity was merged with her husband's identity, and she had no legal rights or property of her own.

For example, if a married woman owned property before marriage, it would become her husband's property after marriage. Similarly, any property acquired during the marriage would be considered the husband's property, even if the wife contributed to its acquisition.

This doctrine was based on the idea that marriage created a single legal entity, or "unity," between husband and wife. It was only in the late 19th and early 20th centuries that laws were passed to give married women more legal rights and recognition as separate individuals.

One example of such laws is the Married Women's Property Acts, which allowed married women to own and control their own property. Another example is the spousal-unity doctrine, which held that a husband and wife could not be witnesses against each other in court. This doctrine was also abolished in many jurisdictions.