Such a right has been recognized throughout American history, as a defense against a charge of battery (under criminal law or tort law). In this case, the state trial judge seemed to conclude no such right existed, at least in public, saying,

If you’re in public with your kids, it’s not appropriate to discipline in this fashion.

But yesterday, the Massachusetts high court unanimously reversed, in Commonwealth v. Dorvil, concluding that there was indeed a common-law right to spank:

[A] parent or guardian may not be subjected to criminal liability for the use of force against a minor child under the care and supervision of the parent or guardian, provided that (1) the force used against the minor child is reasonable; (2) the force is reasonably related to the purpose of safeguarding or promoting the welfare of the minor, including the prevention or punishment of the minor’s misconduct; and (3) the force used neither causes, nor creates a substantial risk of causing, physical harm (beyond fleeting pain or minor, transient marks), gross degradation, or severe mental distress….

As with other affirmative defenses, where the parental privilege defense is properly before the trier of fact, the Commonwealth bears the burden of disproving at least one prong of the defense beyond a reasonable doubt.

And the court held that the defendant prevailed under this defense (some paragraph breaks added):

[A police officer] testified that he witnessed the defendant “smack[]” the child once on her clothed bottom. The defendant and the child’s mother testified that he administered the spanking because the child disobeyed his direction to go to her mother, and continued playing on the sidewalk near the street. The Commonwealth offered no evidence that this “smack” resulted in any injury to the child. Under these circumstances, the Commonwealth failed to offer evidence sufficient to prove beyond a reasonable doubt that the defendant’s use of force was unreasonable or not reasonably related to a permissible parental purpose….

The Commonwealth offers two arguments in support of the contrary conclusion. First, the Commonwealth asserts that the judge could have found “that the defendant in his angry state was not disciplining the child at all, but struck her out of anger and frustration.” … [But a]s a means of balancing parents’ right to direct the upbringing of their children against the State’s compelling interest in protecting children from abuse, a focus on a parent’s emotional state is at once over- and underinclusive.

It is understandable that parents would be angry at a child whose misbehavior necessitates punishment, and we see no reason why such anger should render otherwise reasonable uses of force impermissible. Conversely, we see no reason why the Commonwealth should be barred from protecting children against unreasonable methods of discipline — methods that, for instance, threaten serious physical or emotional injury — simply because it lacks evidence that a parent acted from anger. As the facts of this case aptly demonstrate, moreover, interactions between parents and children may appear ambiguous to outside observers and are susceptible to misinterpretation, leading to significant difficulties of proof at trial and heightened risk of wrongful convictions.

Second, the Commonwealth notes that the child at issue here was two years old at the time of the spanking …. While we agree that a child’s age is one among a number of factors to be considered in assessing the reasonableness of corporal punishment, we reject a bright-line cutoff age below which any corporal punishment is impermissible. The child here was approximately one and one-half months away from her third birthday at the time of the incident. According to her mother’s uncontroverted testimony, she spoke “very well,” communicated “in full sentences,” and was “very advanced for her age.”

Indeed, her response to her father’s direction that she go to her mother — “[N]o, you go to your mother” — evinces a well-developed verbal acuity. According to the defendant’s testimony, moreover, he warned the child of the impending punishment before administering it, stating that “daddy will pow pow, if you don’t stop.” Under these circumstances, the Commonwealth failed to offer sufficient evidence to prove that the defendant’s use of force was impermissible because the child lacked the capacity to understand or appreciate the reason for the punishment.

Sounds right to me, though my wife and I have generally chosen not to spank our own children.

Note that the court mentioned parents’ constitutional rights, citing the cases recognizing such rights and noting that “[t]he widespread recognition of a parental privilege defense accords with important constitutional values.” But the court had no occasion to decide whether there is a constitutional right to spank, notwithstanding a legislative prohibition on spanking — in Massachusetts, the legislature had apparently been silent on the subject.