I think it will be very difficult to implement! Checking the uniqueness of the content will be hard. Users should understand for themselves what they are doing!

Recommendation! Plagiarism can be tolerated, but with some limitations in the percentage. Moreover, it would be more effective if for plagiarism they simply blocked the opportunity to vote. To the post, which contained plagiarism was simply closed for voting.

Why is that?
Very often people copy some news, as they liked it, and there was no time for rewriting. In this case, I believe that it is just necessary to close access to voting on this post.

What do you think? Maybe I'm wrong from the programming position, since I'm not a programmer(
But, I think that it would be fair!