and之后的句子主干结构为they could take reasonable measures...,to ensure that...pending是目的状语,that引导的从句作ensure的宾语。
状语从句中的省略原则是:如果从句主语与主句主语一致,或从句的主语是it,可省略从句的连接词、主语和be动词,只保留分词和其它成分,从而使语言更加简洁明了。
比如时间状语中的省略、地点状语中的省略、让步状语从句中的省略等。例如:The river is clean where (it is) deep.
参考译文:在严重、紧急的情况下,他们还可以忽视第四修正案的保护。此外,在等待许可令签发期间,他们还可以采取合理措施保证手机里的数据不被删除或篡改。
例句2.While polls show Britons rate "the countryside" alongside the royal family, Shakespeare and the National Health Serivce (NHS) as what makes them proudest of their country, this has limited political support.