Some comments above seem to indicate that US incarceration rate being bigger than that of China means that human rights in China at least is not much worse than those in USA. This may not be exactly what the author intended but I still wish to address this suggestion.
While the incarceration rate of USA is indeed alarming, I think focusing only on this number is misleading. In fact, I think the human rights issues of China totally dwarfs those of USA. And from what I have seen, the human rights issue in China does not seem to be improving like many seem to think. Also, as was pointed out by someone else, China has labor camps which do not enter into these statistics. As far as I know, the number of people in labor camps in China is a state secret, so it is still hard to compare numbers.
There are many groups being persecuted in China, but I will focus on Falun Gong practitioners. I think that the Falun Gong persecution is, when seen in the context of the sheer scale and the severity, the most underreported abuse in the world today. Mainstream media hardly covers it at all, and it seems the majority of people outside Asia do not even know what Falun Gong is.
It is hard to find numbers for how many people in China practice Falun Gong today, but an estimate by the CCP before year 2000 was 70 million people. There may be fewer now after more than a decade of persecution, both because of direct killing and because people were scared into leaving the practice. Anyway, this is about 5 percent of the population. American incarceration rate is about 0.7 percent. Now, not all Falun Gong practitioners are in prison or labor camps, but they are all being persecuted to some degree. And they seem to all be in at least some danger of being victims of forced organ harvesting or otherwise brutally abused.
About forced organ harvesting, let me put that in some graphic detail. Some patient (a westerner or a chinese) orders an organ from a chinese clinic. Someone will then seek out a Falun Gong practitioner with matching bloodtype and whatever is needed. They will then cut the ordered organ out of his body, often while he is still alive and often not sedated. Then they will kill him and cremate him (to remove all evidence). And these are state controlled operations, and they have been happening on an increasingly bigger scale.
Here is a video which gives some background.
... the video is made by New Tang Dynasty, which may be a bit partial, but my understanding is they have a good network of reporters inside of China, and they seem to have a high press-ethical standard. If you are still not convinced, the movie also refers to many other sources you can investigate, like David Matas and David Kilgour. Amnesty International has also repeatedly reported on human rights abuses toward Falun Gong practitioners and other groups, so the question really is just how far the CCP has been willing to go, not whether abuses have taken place.
Here is an EU resolution on organ harvesting in China, which I feel adds some weight to some of the claims from the video.
Maybe the strangest thing about this is, the Falun Gong group is not a danger to China. Falun Gong practitioners are explicitly asked to follow the laws of the country one happens to be in and not to entangle themselves into politics. It is a spiritual movement with strict rules to improve oneself, so-called self cultivation. One popular theory is that the CCP looked at the number of practitioners and decided this in itself made them a threat.
There are of course numerous other violations performed by the CCP. But their tight grip on the media and other aspects of chinese life makes it very hard to expose them, and this makes it far easier for the CCP to get away with huge violations of human rights. USA may be slowly deteriorating into a similar society, but they are not there yet.