
Choice is central to intrinsic motivation--when people "fully endorse" what they are doing (Deci et al, 1995).
The assertion of authority while preserving the experience of choice requires substantial integrity, humility and openness. Key elements include: (a) setting direction out of service to a vision as opposed to a desire to control; (b) using active listening to elicit employee experience even if negative; (c) allowing as much choice as possible about design of implementation--how things will get done; (d) providing support through positive teamwork, coaching and training; and (e) ensuring skillful feedback.
For more information see the blog post The delicate balance of positional power and empowerment and the article Two Ingredients to Enhance Speed and Results.