Curbs on business-method claim【主语】// would be //【谓语动词】//a dramatic about-face 【表语】//because it was the Federal Circuit itself that introduced such patent with its 1998 decision in the so- called State Street Bank case, approving a patent on a way of pooling mutual-fund assets【原因状语从句】.

解答：approving a patent on a way of pooling mutual-fund assets.现在分词作结果状语成分

句子整体框架结构是“Curbs+定语+would be a dramatic about-face +because原因状语从句+it was +名词短语+that强调句型”

【1】主句：Curbs on business-method claim would be a dramatic about-face (主谓表结构)

 【2】从句：because it was the Federal Circuit itself that introduced such patent with its 1998 decision in the so- called State Street Bank case, approving a patent on a way of pooling mutual-fund assets.(原因状语从句)

备注：原因状语从句里嵌套一个“It was+名词短语+that ”强调句型，强调句型是“强调句子主语成分”和一个现在分词作结果状语。

Curbs on business-method claim would be a dramatic about-face because eitwas the Federal Circu itself that introduced such patent with its 1998 decision in the so- called State Street Bank case, approving a patent on a way of pooling mutual-fund assets.

Approving引导的分词分句作非限制性修饰语，修饰decision：

decision in the so- called State Street Bank case, approving a patent on a way of pooling mutual-fund assets.

=decision in the so- called State Street Bank case, which approved a patent on a way of pooling mutual-fund assets.

再比如：

The apple tree, swaying gently in the breeze, was a reminder of old times. ["which was swaying gently in thebreezwe] ·