Maybe Lyman and I are painting too bleak a picture of measurer harassment around here. Actually I haven't been stopped for a few months now(!), and I have learned a few rules of the road, mostly learned the hard way.
1. Never try to use any paint on the U.S. Capitol reservation
2. Learn the boundaries of that territory (it's more extensive than you might think)
3. Don't whip out a camera on the pentagon plantation. They are watching and you will be swooped down upon! Always best to let the Lieutenant for Pentagon Police know you are doing some work there.
4. Park Police, who control Independence and Constitution Avenues as well as parks-- hit and miss, and I've actually run into some pretty nice folks but that isn't guaranteed. For the Army Ten Mile course I carry the work order right along with me and some sort of paper from the Park Police OK'ing the work.
5. DC police (MPD) usually leave you alone but for those occasions when they stop to ask you questions, it helps to give some names in SOD (special operations) Dept.
6. Don't even think about riding without ID.
Hmm. A lot of stuff to remember I guess. But on the plus side, I haven't (yet) been actually arrested!
Knock on wood.