a principle holding that an action is permissible 怎么理解啊

感觉是个后置定语，可是怎么理解啊
that 作什么用？
还有该怎么翻译呢？

Although it ruled that there is noconstitutional right to physician-assistedsuicide,the Court in effect supported the medicalprinciple of "double effect",a centuries-old moral principle holdingthat anactionhaving two effects—a good one that is intended and a harmful one that isforeseen—is permissible if the actor intends only the good effect.
【词汇突破】constitutional 宪法的
physician-assisted suicide 医生帮助下的自杀
permissible 可以被允许的
【主干识别】the Court supported the medical principle of "doubleeffect" 主谓宾结构
【其他成分】Although it ruled that there is no constitutional right tophysician-assisted suicide状语从句；in effect作状语；a centuries-old moral principle holding that an action having twoeffects—a good one that is intended and a harmful one that is foreseen—ispermissible if the actor intends only the good effect整个都是themedical principle of "double effect"的同位语。
【微观解析】a centuries-old moral principle其后被 holdingthat an action having two effects—a good one that isintended and a harmful one that is foreseen--is permissible if the actorintends only the good effect. 所修饰。holding that +宾语从句，其中主干为：an action is permissible；having two effects修饰 an action；a good one and a harmful one为two effects的同位语，被that isintended和that is foreseen两个定语从句所修饰；if the actor intends only the good effect为宾语从句的状语。
【难点揭秘】这个句子的复杂就在于同位语的复杂，同位语中有现在分词短语带上宾语从句，在宾语从句中又出现同位语，同位语中又出现定语从句。这样的句子虽然复杂但是还是从最简单的结构一步步搭建出来的。the Court supported the medical principle of "doubleeffect"解释什么叫double effect；“holding that+宾语从句”修饰double effect；an action having two effects is permissible为宾语从句的主干；agood one that is intended and a harmful one that is foreseen 解释什么是twoeffects；if the actor intends only the good effect 为状语从句。
【译文赏析】尽管最高法院已经裁定出医生帮助下的自杀行为并不受宪法的支持，但最高法院实际上支持了被称为"双重效果"的医疗原则；这个已有几个世纪历史的道德原则认为一个行为可能会有两个效果———一个想要达到的好的效果和一个已经预见到的有害的效果。如果行为的实施者想要的只是要好的效果的话，这个行为是被允许的
【翻译点拨】对于同位语的处理我们还是采取了惯用的单独成句的方法，也用到了破折号解释的方法。

您的问题很简单。呵呵。百度知道很高兴帮助您解决您提出的问题。 原句：a principle holding that an action is permissible 翻译：一个原则认为,某种行为是允许的 不是的。 that 解释说明，是代词 宾语从句 百度知道永远给您最专业的英语翻译。

Although it ruled that there is noconstitutional right to physician-assistedsuicide,the Court in effect supported the medicalprinciple of "double effect",a centuries-old moral principle holdingthat anactionhaving two effects—a good one that is intended and a harmful one that isforeseen—is permissible if the actor intends only the good effect. 【词汇突破】constitutional 宪法的 physician-assisted suicide 医生帮助下的自杀 permissible 可以被允许的 【主干识别】the Court supported the medical principle of "doubleeffect" 主谓宾结构 【其他成分】Although it ruled that there is no constitutional right tophysician-assisted suicide状语从句；in effect作状语；a centuries-old moral principle holding that an action having twoeffects—a good one that is intended and a harmful one that is foreseen—ispermissible if the actor intends only the good effect整个都是themedical principle of "double effect"的同位语。 【微观解析】a centuries-old moral principle其后被 holdingthat an action having two effects—a good one that isintended and a harmful one that is foreseen--is permissible if the actorintends only the good effect. 所修饰。holding that +宾语从句，其中主干为：an action is permissible；having two effects修饰 an action；a good one and a harmful one为two effects的同位语，被that isintended和that is foreseen两个定语从句所修饰；if the actor intends only the good effect为宾语从句的状语。 【难点揭秘】这个句子的复杂就在于同位语的复杂，同位语中有现在分词短语带上宾语从句，在宾语从句中又出现同位语，同位语中又出现定语从句。