Meaning changes with time:
Change in meaning of words with change in setting and passage of time.
A phrase begins life as a literary expression; its felicity leads to its lazy repetition; and repetition soon establishes it as a legal formula, undiscriminatingly used to express different and sometimes contradictory ideas.
The phrase ‘assumption of risk’ is an excellent illustration of the extent to which uncritical use of words bedevils the law.
Thus, in the setting of one set of circumstances, ‘assumption of risk’ has been used as a shorthand way of saying that although an employer may have violated the duty of care which he owed his employee, he could nevertheless escape liability for damages resulting from his negligence if the employee, by accepting or continuing in the employment with ‘notice’ of such negligence, ‘assumed the risk’. In such situations ‘assumption of risk’ is a defense which enables a negligent employer to defeat recovery against him. In the setting of a totally different set of circumstances, ‘assumption of risk’ has a totally different meaning. Industrial enterprise entails, for all those engaged in it, certain hazards to life and limb which no amount of care on the part of the employer can avoid. In denying recovery to an employee injured as a result of exposure to such a hazard, where the employer has in no sense been negligent or derelict in the duty owed to his employees, courts have often said that the employee ‘assumed the risk.’ Here the phrase ‘assumption of risk’ is used simply to convey the idea that the employer was not at fault and therefore not liable.
[Source: TILLER vs. ATLANTIC COAST LINE R. CO., 318 U.S. 54: 63 S.Ct. 444: 87 L.Ed. 610 (per Frankfurter J.)]
A word is not a crystal, transparent and unchanged, it is the skin of a living thought and may vary greatly in color and content according to the circumstances and the time in which it is used.
[Source: Towne v. Eisner, 245 U.S. 418, 425 (1918) (per Holmes, J.)]
Mystery of Law and Justice 