英语翻译Recourse will then be had to an occasion in the past on which a great anxiety provedto have been without real justification,having,indeed,been refuted bythe outcome.

这样的理解?
追索权产生于这样的一个情况下, (当事人)被对方无任何正当理由所驳斥.

Recourse will then be had/ to an occasion in the past/ on which a great anxiety proved to have been without real justification, having, indeed, been refuted by the outcome.
1. 句子意群解析：
追索权那么将被拥有/ 在过去某个时候/ 在这个时候/ 一个被证明没有正当理由的极大的焦虑/已经/确实地/被结果所驳斥.

串起来的意思就是：
在过去当某种（迫切的）愿望被证明没有正当理由、并且已经确实被结果所驳斥的时候,可以诉诸追索权/可以寻求援助.

1. 这句话的句子分析：
Recourse will then be had：主句
to an occasion in the past：状语
on which a great anxiety proved to have been without real justification：对occasion的定语从句
having, indeed, been refuted bythe outcome.对proved... justification的修饰状语,表示时间先后.意思是确实在被结果证明驳斥之后,是作为一个插入的状语.
本来原句是on which a great anxiety,(having, indeed, been refuted by the outcome), proved to have been without real justification. 这种诉求（已经被结果所驳斥）被证明是没有正当理由的.

这句话的难点在于结构比较复杂,插入的成分比较多.而且结构都相似,让人误以为是不是弄错了,但实际上不是的.要仔细分析后方能得知.

水平有限,不当之处请批评指正.谢谢!