I must agree with many of the other response posted and say that much of the content was not news to me – constant news reports on the systematic widespread of arbitrary government power in China have kept me up-to-date on this topic.
Professor Cohen’s story of Changwon Chang(?), the legal activist who was sent to prison for 3 years and 4 months, triggered my interest the most. Despite the Chinese Constitution purporting to guarantee freedom of speech, I am surprised to see how much the Chinese government is willing to suspend the rule of law and continue to suppress dissenting opinions and maintain political control over the media. For example, I recently read an article about internet censorship and regulations implemented in China to repress what the government views as critical to the regime. As Professor Cohen has pointed out, the media is an essential tool in promoting and strengthening the rule of law and, ultimately, the development of a fair and just legal system. The media being so heavily influenced (or controlled) by the communist party is, not only disparaging the implementation of a rule of law, but also jeopardising the basic rights of citizens. 
On another note, as Professor Cohen has indicated, China has indeed seen a significant progression in the development of the legal system and education over the past 30 years. However, this bears little significance in practice when there is lack of accountability in the legal institution – as it is profoundly weak and is still finding it difficult to enforce judgements – and the communist party continues to maintain influence, or even control, the legal arena. As many have suggested on the blog site, separation of powers appears crucial to preserve, not only the rule of law, but also the basic human rights of Chinese citizens from arbitrary use of power by the government.
The rule of law can be defined as being the superior rules above the political arena that dictates say how the government should govern and also entails that the government is subject to the law as all other citizens – to use Professor Cohen’s definition of the rule of law, “Government under Law”. In this sense, it is undoubtable that the rule of law is essential and necessary in China to protect individual rights from being compromised by oppressive conduct by the communist party.

To JFerris,

The values of rule of law, of human rights, and of democracy are fruits of human civilisation, universally influential; the associated legal system of a well-established jurisprudence are pervasive and attractive to others. A carefully tailored legal system is the core of a civilisation of the age, and will be borrowed by many others. The globalisation and transplant of legal system have already brought many values and standards into the Chinese society.

By short-cut, I mean the construction of modern legal system in China has been influenced by and even based on the embracement of many experiecences of many west countries. The techniques of law-making and enforcement matter very much; and the skills of modern governance of a nation are just what the Communist Part need to learn (I'm talking about "social governance", not "reign" or "ruling").

In terms of police power, there are criminal Code and criminal procedure code defining the power of the police. The power has been limited and things are chaning. In very abnormal case, there are abuse of police power. But, I don't think the police in any other country would behave better than Chinese police! I was in many countries and never find any police who are more friendly and helpful than Chinese police. If you don't believe, go to China, and call 110 for help, you will see how the Chinese police would behave. If bad, it would not be worse than the police of any other country.

There are defects in the allocation of police power in China; but there are also counterbalance. For instance, Chinese police are much more engaged with the local community. In Chinese community, people are very close to each other and people know each other. If you don't behave well, people will know and people will judge you. It might be a kind of power restricting the police power. But, as I said, in some extremely abnormal cases, particularly when core political interests involved, there are visible abuse of power...in this case, police might not be the one who act but the one who is behind the police. That is the political power, ugly and unbounded political power!

In summary, there are emerging rule of law in China; but but but not nearly accomplished at all! And, with the test of "goverment udner the law, any political party under the law", people can see the very visible reality of rule of law in China.