三个单词均有能力的含义。ability为通用词，指天生或后天所得的干好某事的能力，尤指实施法律行为的权力（利）（power to carry out a legal act)⑴，如 the ability to enter into an agreement with others。相比之下，faculty则主要指某种特殊行为的天赋能力，在离婚案件中可指丈夫对妻子提供扶养费的能力[2]。 capacity (也称为legal capacity)多表示在法律或其他意义上的一种地位或资格[3]。
[1] “ The capacity to perform an act or service； esp. the power to carry out a legal act. ” Cf. Bryan A. Gamer, Black's Law Dictionary, 7th edition, at p. 4, West Group (1999).
[2]“ In the law of divorce，the capability of the husband to render a support to the wife in the form of alimony, whether temporary or permanent, including not only his tangible property, but also his income and his ability to earn money. ” The Publisher's Editorial Staff, Black's Law Dictionary, abridged 6th edition, at p. 411 , West Publishing Co. (1991).
[3] "The legal ability or qualification to perform an act having legal consequences, such as entering into a contract，making a will, suing or being sued，committing a crime，or getting married. * Cf. James E. Clapp, Random House Webster's Dictionary of the Law, at p. 69, Random House (2000).