The NZ/Aust Office Max website Colour My World is where you can create a handwriting pen licence for your pupils - it can be printed out and used/laminated/displayed etc.
I give the pupils the original (larger size) to take home; I put the middle sized copy on display in the classroom for quick reminders of who is allowed to use pen for writing (in all of their work except maths) and I laminate the smallest size for the pupils to keep in their pencil case as a personal reminder that they have a standard to uphold!
As an awesome bonus, the pupils will soon each receive in the mail their own little congratulatory pen pack thanks to the sponsors of the site (Office Max)! The small laminated licence is presented to the pupil when the pen pack arrives. Kids love it and it motivates the others to try to improve their writing style.
If a pupil's standard slips, then they have to hand over the licence - doesn't happen very often!