How can I most respectfully leave my current PhD position for a new one? My professor is a bully and the university will not challenge his behaviour despite numerous complaints from both staff and students. I am 9 months into the first year of my PhD. I love my work and all of my other colleagues but the professor's behaviour is unbearable and affecting my mental health. I have made the decision to apply for positions elsewhere. 

How can I do so without appearing as a troublemaker? I am terrified that other lab groups will read my application and just see me as weak, lazy, or disruptive for leaving my current position. How can I mention the experience of my current position on my CV, and explain politely in cover letters etc. the circumstances without sounding like a brat?

Thanks in advance,

A very stressed PhD student
If you are moving to a new university, I think you can ignore most of your fears. You need to get accepted, of course, and may require letters of recommendation to do so, but I don't think you need to be very explicit about disagreements with your supervisor or your assessment of his flaws. It is enough, for most purposes, to simply indicate that you had an incompatible position and are seeking a better one. Keep any disagreements out of your written materials for application. If you are asked, don't emphasize the disagreements or the treatment. The old advisor probably isn't going to change and you are interested in finding a better situation rather than correcting the old one. 

Write your materials, initially, as if you were starting fresh. Then add just enough to show that you are in an unhappy situation and want a better one. Don't try to hide it, but emphasize the positive. 

I suspect that, except in a few narrow fields, what people think of you at the old place won't matter much if at all. The old professor may be known and can have some impact (hence being cautious), but other people in the lab are pretty invisible from the viewpoint of another institution. 

On your CV, mention your current position, of course but without comment. In your SOP stress that you find your current situation "unsatisfying" and "not sufficiently productive". 

While it may be unsatisfying not to complain about bad behavior, doing so from a position of little power can hurt only you.