My college-aged daughter tried to persuade my husband and me that it would be best for her to return to campus after spring break and complete her senior year of online classes from her apartment with her young and healthy roommates. She argued that they aren’t in the demographic likely to contract the new coronavirus and even if they did, they would be very likely to recover.

My husband and I countered that even if the risk to her is small, she may carry the virus and the consequences for others may be quite large. We recommended that she stay at home and self-isolate with us.

I knew this principle was the bedrock of our tort law and was able to refresh my recollection easily. In United States v. Carroll Towing, 159 F.2d 169 (1947), a tug set out to remove one of a series of barges moored at Pier 52 in New York Harbor. After removal of a certain mooring line, several barges broke free and the barge Ana C, loaded with flour owned by the U.S., sank.

In deciding the indemnity action filed by the U.S. against Carroll Towing Co., Judge Learned Hand noted that there was no general rule that applied liability to the situation when a barge breaks free with no one on board and causes damage. He noted there were three variables to the tugboat owner’s duties in the situation: the probability that the vessel will break away, the gravity of damage that results if she does so, and the burden of adequate precautions.

In finding against the barge owner, the court noted that leaving a barge unattended during daylight hours posed a significant risk such that it would be fair to require a crew member to be aboard the ship. Judge Hand proceeded to state a famous negligence formula: a defendant is negligent if he creates a risk where the probability of the risk occurring (P) multiplied by the seriousness of the risk if it materializes (L) is greater than the burden of eliminating the risk (B). Thus, the algebraic Hand formula: the defendant is negligent if B<PL.

We are living in a time of a new and highly contagious coronavirus that disproportionately impacts older adults and people who have severe underlying chronic medical conditions. The virus may be undetected in many carriers. We are told the risk drops dramatically by hand washing and social distancing.

Applying Judge Hand’s analysis: the probability of the risk occurring (the coronavirus spreading) multiplied by the seriousness of the risk if it materializes (potentially fatal to some people) is much greater than the burden of eliminating the risk (self-isolating).

The law provides a steady hand in uncertain times. My daughter will be staying at home.

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