Dispute over order of authors Consider this situation.

A research plan is formulated for a masters student (M) collectively by a professor (P) and a PhD student (G). M runs the experiments but has no idea how to extract knowledge from his experiments (he is not motivated enough to make the effort). P asks G to 'look into it'. G analyzes the data, studies the subject background, identifies some erroneous numbers and re-runs some experiments. G then  drafts a research manuscript for submission to a journal. 

Even though the 'raw' data was acquired by M, it was G who made efforts to discuss the results and transform the data into a manuscript. M argues that since the research plan was a part of his masters dissertation, he should be the first author. To resolve the dispute, P keeps himself the first author, G the second, and M the third.  

Who should be the first author in this case? (The first authorship matters in the field in question.)
There is a fair option available. The professor could have insisted that both M and G could be first author. I have seen in research follows like this:

M*, G*, P or G*, M*, P

* Both the authors contributed equally to this work.

Your present authorship order: P, G, M is really unfair for both of you (G and M).