Wiktionary
standard of care
n. (context legal English) In tort law, the degree of caution that a reasonable person should exercise in a given situation so as to avoid causing injury.
Wikipedia
Standard of care
For the English law, see standard of care in English law.
In tort law, the standard of care is the only degree of prudence and caution required of an individual who is under a duty of care.
The requirements of the standard are closely dependent on circumstances. Whether the standard of care has been breached is determined by the trier of fact, and is usually phrased in terms of the reasonable person. It was famously described in Vaughn v. Menlove (1837) as whether the individual "proceed[ed] with such reasonable caution as a prudent man would have exercised under such circumstances".