Current law
In Maryland, as in most states, a person can sue his or her spouse. This includes a lawsuit for breach of contract or a tort action. The rule allowing a spouse to sue for all tort actions was established by the Maryland Court of Appeals by case law in Bozman v. Bozman, 376 Md. 461 (2003). The law allowing a spouse to sue for breach of contract is in statute. A married woman may sue her husband for breach of contract, and a husband may sue his wife for breach of contract. Read the Law: MD Code Family Law § 4-204, 4-205
Maryland's history
In the past, Maryland used to limit the ability of a person to sue his or her spouse. The common law (case law) rule that prohibited suing a spouse was called interspousal immunity. The interspousal immunity rule was based on court holdings that by marriage, a husband and wife become one person in law. Lusby v. Lusby, 283 Md. 334 (1978).
Blackstone's Commentaries gave the doctrine's rationale:
"By marriage, the husband and wife are one person in law: that is, the very being or legal existence of the woman is suspended during the marriage, or at least is incorporated and consolidated into that of the husband: under whose wing, protection, and cover, she performs everything; and is therefore called in our law-french a feme-covert, foemina viro co-operta; is said to be covert-baron, or under the protection and influence of her husband, her baron, or lord; and her condition during her marriage is called her coverture. Upon this principle, of a union of person in husband and wife, depend almost all the legal rights, duties, and disabilities, that either of them acquire by the marriage." He adds, in discussing the consequences of this union of husband and wife, "If the wife be injured in her person or her property, she can bring no action for redress without her husband's concurrence, and in his name, as well as her own: neither can she be sued without making the husband a defendant." Quoted in the Bozman case, at page 469.
In the Bozman case, the Court of Appeals noted that the interspousal immunity doctrine was “a vestige of the past, whose time has come and gone.” Bozman case, at page 497.