How can I address a student systematically boosting their grades by filing frivolous complaints? I was recently accused of unfair grading by a student.  The accusation is meritless, and it didn't take long to prove that I didn't do anything wrong.  No damage, but a lot of time wasted.

Later, I learned through the grapevine that I was among a long list of victims.  Indeed, in just one year, the very same student filed formal complaints against at least nine professors.  The nature of the complaints vary from case to case, but they follow the exact same script:


In every case, the student will take some small thing, e.g. a missed quiz or a late homework, and make a big argument with the instructor out of it.  The student will then escalate the issue to higher level and get the dean of college or even the president of the university involved. Of course the dean or the president have better things to do, so the student is usually ignored and the whole thing blows over quickly … or so we thought.  This part turns out to be only the lead jab in a one-two combination.  It's more of a setup.
The real strike comes at the end of the semester. When the grade is not good (which is 100% of the cases), a formal complaint will be filed stating that the student was punished for the earlier argument.  This is a very serious accusation and lead to complicated investigations in several cases.  It caused so much additional work that several professors just gave in and changed the grade to something the student liked.


This trick had a surprisingly high success rate, especially considering several victims are tenured professors.  The student is emboldened, and I have no doubt that the cycle will repeat.  If not stopped, I wouldn't be surprised if this student can earn a degree just by reusing this trick again and again.

My question is: Should we professors (as a group) react to such a behaviour and if yes, how? What could be the consequence, if any?

So far I have read the students' code of conduct carefully.  There appear to be nothing that can be directly applied here.  The closest appears to be the rule about dishonesty, but it wouldn't work by itself.

Updates:


After sharing parts of this story, I received several similar stories from friends and colleagues in other universities.  So the situation I described here is perhaps not as unique as it first appears.  It turns out, in my previous university, the department chair handled two similar cases while I was there.  But because such cases are supposed to be confidential, I was not aware of them.  I suspect this happens more often than we think.
The student does not have to prove his/her claim for this trick to work.    He/she simply has to file a complaint and a grade change appeal at the same time.  Students' have the right to do those.  That will trigger a lot of work for the instructors, the department chair, and the dean's office.  In my case, it took me 20~30 hours to respond to the complaints, provide assignment for review, and do other works.  Not everyone has this kind of time on the last day of the final week.  Given the options of doing these extra work vs. changing a letter and let it go, not everyone will make the right choice.


More update:


This student scored one more win:
The grade appeal committee's new ruling is that I should/have to change my grade (one letter grade higher) even though it was determined that I did not do anything wrong.
I now realized the student's trick work on multiple levels: It just keep on throw in serious accusations. At some point, someone, will feel it would less trouble to just give him/her what he/she was asking for. The instructor does not have give in. It could the departmental committee, or the chair, or the associate dean, or the college committee,... The only way this trick fails is that every single person along this long chain stand their ground.
When it comes to "he-said, she-said" situations, as seems to be the case here, most institutions will tend to take the side of professors by default. For obvious reasons—the 18–22 year old college student is much more likely to lie to obtain a favourable mark, than the professor is to act maliciously to sabotage a student. The only scenario where the professor might be in trouble is if there are accusations from multiple students. 

The most significant red flag here is that the student is making essentially the same accusation against nine different professors. It is preposterous that nine professors would collectively decide to sabotage a single student. 


  So far I have read the students' code of conduct carefully. There appear to be nothing that can be directly applied here. The closest appears to be the rule about dishonesty, but it wouldn't work by itself.


Making dishonest accusations to obtain more favourable grades is an unequivocal form of academic dishonesty. Any respectable institution would discipline a student engaging in such behaviour. If this behaviour cannot be disciplined at your university, I would suggest seeking employment elsewhere. 

You should lodge a formal complaint, possibly in collaboration with the other professors who are being accused. You have a rock-solid case.