I am directing a piece in an upcoming New Play Festival. I was looking over the guidelines, which they sent out to directors and playwrights, and I thought I would post this paragraph which seems like a pretty sane and level-headed view of how playwrights and directors should work in this type of an environment. (The italics and capitals are their emphasis.)
Regarding Playwrights – VERY IMPORTANT, READ THIS CAREFULLYA focus of the festival and a hallmark of our success have been to highlight the work of local playwrights of extraordinary talent. They are welcome to come to rehearsal and you should contact them early in the process to have a dialogue about their piece. Normally this tends to be informative and intriguing. However, you may hold some rehearsal without them if you feel you need some time alone with actors. The roles of playwright and director are held with deep respect at our Company. THIS CANNOT BE STATED MORE EMPHATICALLY. Playwrights should not direct actors, do line-readings, mandate blocking, etc. By the same token, directors should never change a line or stage direction in the script without permission of the playwright, and should not seek to alter the overall message or appeal of the play in any way. Please treat Playwrights with the utmost respect and kindness. If a conflict arises at any time, please contact me immediately so that we can clarify parameters and clear the air with professionalism. Theatre is by nature a collaborative and nurturing art, however, it should also be treated as a professional one with clear roles for all involved, so that everyone is respected.