"Washington, D.C.: Will the police come down pretty hard on unpermitted protests, or will you let them go since it is a holiday weekend and disruption will likely be small?
Alfred Broadbent: The police would recommend that all groups that want to march on public space obtain a permit. Permits can be obtained by responding to our Special Operations division located at 23rd and L St., NW.
The reason the police recommend that you obtain a permit is so that they can ensure the safety of the marchers while they are on public space and also to plan around dignitary movements of the president and other foreign dignitaries who might be traversing the streets of Washington. "
It's an old article (2003) but I would this is where we should start ...
http://www.ronpaulforums.com/showthread.php?p=1247172
Secure a permit for your demonstration. Contact the National Parks Permit Office by calling (202) 619-7225. Ask them to fax you a permit application. Ask them for the availability dates on the gathering location, march route and rally point. Once they have confirmed availability, proceed to fill out the entire application. Make sure to specify the estimated number of people participating in the protest and the main contact person. That person must sign and date the application. Make a copy of the application and the highlighted map for your records. Mail the original application and highlighted map to: National Parks Permit Office, Room 128, 1100 Ohio Drive Southwest, Washington, District of Colombia 20242. Wait about a week for a National Parks Agent to call. This agent will be specifically assigned to your organization for the permit application process. Have the agent give you her direct extension for further questions and information. Provide the agent with any additional information he may need to approve the permit. Ask him to fax you the approved permit immediately and mail the original back to you.