What to do if one has had an unsuccessful PhD (because of others' fault)?

There sure are cases, every now and then, of researchers (professors or other) abusing students in various ways. As everyone, I have heard stories, and I know at least a couple of people who have been put in dramatic situations during their PhD. However bad the behavior of the advisor is, it turns out that there are multiple venues one can try, during the PhD, when the alarm flag is raised. These depend on the institution and type of employment, but they include:

• Going to see the PhD program director, explaining your situation (diplomatically) and asking for advice (read: help).
• Finding a friendly researcher/professor in your department, and ask him for advice (and possibly help) with your issue. They know the people and local “politics”, and might have efficient advice.
• Your employer's HR department
• Going to your professor's hierarchy (department chair, dean, …). As a last recourse, file a formal complaint.
• Get someone to speak for you: a union representative, a member of the local “PhD association”, etc. That can help if you are worried about the fallout of intervening directly.
• Changing your plans to work on a more “independent” research. In your example, your friend was denied access to a given experiment. If the experiment had broken down beyond repair, he sure could reörient his research, so the same thing could be done in the case at hand (I'm not saying it's easy).
• Walking out (or, as JeffE would surely say: don't walk, run!)

Regarding legal action: I don't think this avenue can lead anywhere, unless there is factual evidence of gross misconduct or unethical activity. The burden of proof relies on your friend, and I think it will actually be harder to complain after the fact if he did not raise his concerns formally during his PhD.

If it is likely that he will pass, your friend should go for the defense first, every other aspect put on hold. As for a court case, it is risky; they will have to prove that they were harmed intentionally or through negligence (I am not sure the latter counts in a supervision process - I am not a lawyer!).

They will also have to prove that the postdoc basically took the ideas from them. This is quite possible and definitively does happen, however, keep in mind the possibility that it might have been the other way round: sometimes students underestimate how much they have absorbed from the research group and their superviser and believe that they have had an original idea, whereas they only had the final "flash of understanding" about what their supervisors and group colleagues have been talking about for months.

An emotional situation may cloud their self-judgement with respect to their contribution and taking it to court is not recommended, unless they are absolutely sure their idea was taken and they can prove it. Even so, it might not be a good idea, because these are murky waters. I have known a case of a student being upset at their supervisor only to come back a period later - with more life experience - to complete a joint paper broken off in anger, because he understood how much the supervisor had contributed in the first place.

Finally, not every PhD is a success story in terms of concrete scientific achievements - this may depend on talent, luck, circumstances. However, if your friend passes, they have achieved a PhD in 3 years and, no matter what, that's a pretty good achievement. Some PhD's (esp. in Europe) drag on for 6-7 years, others never materialise. So, while it may not look like it at this point, after the PhD, things may look brighter to your friend.