why is any of the above relevant?
it is perfectly possible to suffer from a poor supervisor in your final year. Obviously it's possible to do well even with a poor supervisor, but it does make it a lot more difficult. I am firmly of the opinion that my degree suffered a difference in classification because of the actions (or lack of) from my supervisor. Essentially I had positive feedback, positive feedback, positive feedback -> handed it in, marked by same supervisor -> poor mark. I depended on the feedback from my supervisor and my result suffered from that feedback being poor.
I wouldn't have sued, but I did come close to appealling my grading.