Defense一词在法律英语中有以下几种含义：

1.答辩，辩护；辩词；答辩理由，指民事诉讼中被告对原告起诉状中的主张和请求，或者刑事诉讼中被告人对控诉方的指控所作的否认、反驳，以及支持被告人反驳主张的理由、证据等；如：The defence was that the records of the interviews were fabricated by the police.答辩词是警察捏造了访谈纪录。

2.辩护方；(被告对指控的)答辩；被告律师；The lawyer or lawyers whose job is to prove in court that a person did not commit a crime.

3.(对非法暴力行为的)反击；防御；防卫。如self-defence即为自卫，The man later told police that he was acting in self-defence.事后那人告诉警察，他当时是出于自卫。

Affirmative defense，翻译为“肯定性答辩；积极的答辩”，A defendant's assertion of facts and arguments that, if true, will defeat the plaintiff's or prosecution's claim, even if all the allegations in the complaint are true. 根据元照词典，肯定性答辩是指被告并不否认原告所主张之事实的真实性，而是提出其他的理由来说明为什么自己不应承担责任的答辩。因此，它并不反驳原告诉求之真实性，而只是否认原告在法律上有起诉的权利。根据联邦及大多数州的民事诉讼规则，所有的肯定性答辩都必须在应答书状〔responsive pleading〕即答辩状〔answer〕中提出，且被告对其所提之事由负证明责任。这些事由包括和解和清偿〔accord and satisfaction〕、自担风险〔assumption of risk〕、混合过失〔contributory negligence〕、胁迫〔duress〕、时效、不容否认〔estoppel〕等。在刑事诉讼中，构成肯定性答辩的事由包括精神失常、醉酒、自卫、无意识行为〔automatism〕、不在犯罪现场〔alibi〕、受胁迫等。

Capacity defense，翻译为“能力欠缺抗辩”A defense based on the defendant's inability to be held accountable for an illegal act or the plaintiff's inability to prosecute a lawsuit，刑事责任能力欠缺辩护指欠缺可构成诉讼的基本能力。例如，某人因受胁迫而欠缺合同的意思能力，后如因此合同而被起诉，则其可提出能力欠缺抗辩。

参考双语例句：

①For example, this may include experience in the following areas: the defence of those charged with serious and complex crimes at the domestic level, such as terrorism, homicide, manslaughter, trafficking and complex white-collar crimes; the defence of cases with international dimensions, such as those involving international judicial assistance, complex immigration issues or supranational crime; and the defence of those charged with war crimes, genocide and crimes against humanity.

举例而言，这可包括以下领域的经验：国内严重和复杂罪行的辩护，如恐怖主义、杀人、非预谋杀人、贩运和复杂的白领罪行等罪案；涉及国际层面的案子的辩护经验，诸如国际司法协助、复杂的移民案、超国家的罪行；以及战争罪、灭绝种族罪和危害人类罪的辩护经验。

②One of the challenges ahead is to extend the tailored capacity-building, which currently reaches judges and prosecutors, to other professional groups of the criminal justice system such as defence lawyers, attorneys representing victims and correctional officers.

今后的一个挑战是将目前对法官和检察官开展的有针对性的能力建设活动，推广至刑事司法系统的其他专业群体，诸如辩护律师、受害人诉讼代理和管教人员。

③It was his delegation’s understanding that the agenda item on assistance in mine action was intended neither to universalize the two conventions for States parties nor to impugn the “legality” of a State that used landmines in legitimate self-defence.

印度尼西亚代表团的理解是，援助地雷行动议程项目既不想要求缔约方普遍加入这两项公约，也不想驳斥一国将地雷用于合法自卫的“合法性”。