If it were to be parsed, this is what it would look like:
(a) この法律に違反する可能性がある\ (b) 政治の \ 団体が活動をやめています。
The one in boldface is the core of the sentence. (a) and (b) modifies 団体.
Now, you mentioned this:
The first が: 違反する可能性がある政治の団体 lit. government groups that possibly oppose?
The second が: 政治の団体が活動 lit. activities by government groups? (in retrospect, the ...