Does policy influence math teachers?

Teachers College Record features an interesting article related to mathematics education this week (the article is freely available): Does Policy Influence Mathematics and Science Teachers' Participation in Professional Development, by Laura Desimone, Thomas M. Smith and Kristie J.R. Phillips. Here is an abstract of the article:
Using a national sample of high school mathematics and science teachers from the Schools and Staffing Survey (SASS), we find that authority (teacher leadership and control over school and classroom policy), not power (frequency of evaluation of teachers and professional development, and ease of dismissal of teachers), is associated with teachers taking the kind of professional development that we know improves teaching and learning-activities focused on subject matter content and instructional strategies, as well as active interactions with other teachers around curriculum and instruction. Similarly, we find that stability (measured by reduced teacher turnover), not the consistency of professional development with other reforms, is associated with taking effective professional development.