This happens all too frequently. People tend to think that they are being outranked by sites that scrape their content.
While I am the first to fault google, they do tend to do a pretty good job at recognizing the content source. The reason the site is suffering is likely not due to the fact that its content is being copied by other sources, but by an underlying issue that google is seeing.
Putting the blame on sites copying your content is easy to do but it is not always the reason why you're being outranked. Google may know that you are the source of the content, but maybe it sees your content as being hard to get to or maybe it sees your site as a whole spammy. Usually with issues just like yours, I notice the webmaster is in some sort of over optimization penalty.
I do feel it is wrong for google to rank scraper sites ahead of the source, regardless of what penalty they feel the originator deserves, I think the original source should always get favored over the scrapers.