Yes technically you can carry them without having the writ. But the repercussions of using them without one, or being caught, must be found out in game. There are resources that indicate possible punishments listed on the sidebar under the Baronial Library under In Game tab of the website. That info in the Baronial Library is considered common in game knowledge. There is plenty of role play associated with the legality of them, how and when they are used, and the repercussions.
Elias Ashby
Proprietor of the Ashby Family General Store
Lord Templar Rayven Nightwing of the Order of Holy Light
(OOG - Matt D. - Photographer)