Counterclaim，反诉，指在一个已经开始的民事诉讼(诉讼法上称为本诉)程序中，本诉的被告以本诉原告为被告，向受诉法院提出的与本诉有牵连的独立的反请求。

Counterclaim：A claim for relief asserted against an opposing party after an original claim

has been made; esp., a defendant's claim in opposition to or as a set off against the plaintiff's claim.

Compulsory Counterclaim，强制反诉，是指本诉被告提出的反诉与原告提出的本诉基于同一交易、行为或事件，则本诉被告必须在本诉程序中提起反诉。如果被告不提起反诉，根据既判力的原则，他将丧失权利，产生失权效果，并且在原则上不得另案起诉。是指本诉被告的反诉与原告的本诉不是基于同一交易、行为或事件，此种情况下，被告可依其意志自主决定是否提出反诉。如果被告不提出反诉，也不影响其另案起诉。

Compulsory Counterclaim：A counterclaim that must be asserted to be cognizable, usu. because

it relates to the opposing party's claim and arises out of the same subject matter.

Permissive Counterclaim，任意反诉，是指本诉被告的反诉与原告的本诉不是基于同一交易、行为或事件，此种情况下，被告可依其意志自主决定是否提出反诉。如果被告不提出反诉，也不影响其另案起诉。对于任意反诉，法院是否受理并与本诉合并审理裁判，全凭法官自由裁量。

Permissive Counterclaim：A counterclaim that need not be asserted to be cognizable, usu. because it does not arise out of the same subject matter as the opposing party's claim or involves third parties over which the court does not have jurisdiction.

参考双语例句：

Having received full and detailed written observations from each of the parties, the Court judged that it was sufficiently well informed of the positions they held as to whether the Court could entertain the claim presented as a counterclaim by Italy in its counter-memorial.

在收到当事双方的全部详细书面意见之后，法院判定，法院已经充分了解当事双方就法院可否受理意大利辩诉书中作为反诉提出的申诉所持立场。

The respondent has failed to communicate its response to the notice of arbitration or its statement of defence, the arbitral tribunal shall order that the proceedings continue, without treating such failure in itself as an admission of the claimant’s allegations; the provisions of this subparagraph also apply to a claimant’s failure to submit a defence to a counterclaim or to a claim for the purpose of a set-off.

被申请人未递交对仲裁通知的答复或答辩书而不表明充分理由的，仲裁庭应下令继续进行仲裁程序，不递交答复或答辩书之事本身不作为承认申请人的主张处理；本项规定也适用于申请人未就反请求或为抵消目的的请求提交答辩书的情形。

On 27 January 2010, at a meeting held by the President of the Court with the agents of the parties, the agent of Germany indicated that his Government did not consider the counter claim submitted by Italy to be in accordance with article 80, paragraph 1, of the Rules of Court and that it intended to raise objections to the Italian counterclaim.

法院院长于2010年1月27日与当事方代理人举行一次会晤中，德国代理人表示，德国政府认为意大利提出的反诉不符合《法院规则》第80条第1款，并且打算对意大利的反诉提出异议。

(Mauritius) said that in the absence of the representative of Slovenia, he wished to point out a suggestion from the Slovenian delegation contained in document A/CN.9/704, page 5, which read as follows: “It is suggested to consider whether draft article 21 (4) should also include a reference to draft article 20 (3), to cater for the situation where the counterclaim or claim for the purpose of a set-off would be based on a contract or legal instrument different from the one submitted by the claimant in the statement of claim.

Moollan先生（毛里求斯）说，由于斯洛文尼亚代表缺席，他希望指出斯洛文尼亚代表团在A/CN.9/704号文件第5页中的建议，内容如下：“建议审议第21（4）条草案是否应提及第20（3）条草案，以顾及下述情形：为抵消目的提出的反诉或申诉所依据的合同或法律文书不同于申诉人在申诉书中提交的合同或法律文书。