In Bass v. Nooney Co., the Supreme Court of Missouri abandoned the rule that a defendant is not liable for negligence which produces emotional distress unless the plaintiff suffers a contemporaneous physical injury or impact. This "impact rule" was the majority position in the United States in the first part of this century and had been a part of Missouri's jurisprudence since 1881. In Bass, however, Missouri joined the mainstream of American jurisprudence by providing judicial protection against a plaintiff's loss of emotional tranquility without requiring contemporaneous physical impact.
William M. Hillsman,
After the Impact Rule - Limiting Defendant's Liability in Negligent Infliction of Emotional Distress Cases: Bass v. Nooney Co.,
U. Rich. L. Rev.
Available at: https://scholarship.richmond.edu/lawreview/vol18/iss2/7