First of all I am glad you are engaging in a civilized discussion. Let's follow this protocol.
Before I answer your questions, let me give you three examples:
(1) Bill Clinton was accused having a sexual relation with an intern. At the time, there was no direct evidence for this allegation. As we now know, the evidence is on Ms. Monica Lewinski's dress.
Nevertheless, the public outcry and the media pressure forced president Clinton to step up and make a statement. If you still remember, he made the famous sentence, " I did not have sexual relationship with Ms. Lewinsky."
The investigation started shortly after. Now we know all the results.
Bill Clinton or any of his supporters did not say "show your evidence if you are accusing the President." This, to Americans, is an insult!
(2) The Enron case also involved a whistleblower, Ms. Sherron Watkins. At the time, she had no direct evidence to against Enron. But the sheer scale and the extent of the internal corruption reported was enough to draw attention of any responsible people in the justice department.
What do those stories tell you? They tell you that "without evidence" is not a sole argument to hinder, stop and block legal and judicial investigation of the case! Of course they did not make Clinton and Enron guilty at the time.
(3) Scott Peaterson was accused murdering his wife. However, there was no physical evidence to hold him acountable. But now he is in prison, still without any direct evidence!
In cases like this, it is also time for the government to step in. Grand jury is one of the ways.
In China, I assume it is the government's responsibility to step in too. But do you think they will do it? Obviously China did not do anything. The burden is left for PKU! Ironically, PKU is not only a part of the government, but also the accused! It has the responsibility to answer to the tax payers and concerned citizens!
The result is that PKU chose to do whatever it wants to do. You call this "是中国法律走向进步的标志"? If you are not joking, you must be very ignorant.
(I hope I answered your questions, unless you tell me that US justice system is worse than that of China.)
