Recently, I was run off of the road by a taxi in Laurel, MD. I am pretty sure I know which company was responsible for that cab, but I had to go through a lot of legwork to find enough information to prove it to my satisfaction.
In Maryland, the state regulates sedans, vans (without a dome), and limousines, and each county regulates their taxicabs (which seems to be defined as any vehicle with a dome). The counties each have a division which licenses carriers, and they record the color of each cab company's vehicles, as well as their numbering scheme. (This information is all as of January 26th, 2005.)
In Prince George's County, the division responsible for taxis is:
Prince George's County Business & License Office
6016 Princess Garden Parkway, Suite 370
New Carrollton, MD 20784
(301) 731-7990
In Anne Arundel County, try the:
Department of Inspections and
Permits
Commercial
Licensing Division
2664 Riva Road
Annapolis, MD 21401
(410) 222-7788 or 7790 (I&P main number)
FAX: (410) 222-7970
InspectionsandPermits@aacounty.org
Hours: 0830-1630
In Howard County, the:
Department of
Inspections/Licences/Permits
Licences and
Permits Division
George Howard Building, 1st Floor
3430 Court House Drive
Ellicott City, MD 21043
(410) 313-2455
Hours: 0800-1700
In Montgomery County, the:
Department of Public Works and Transportation
Transit
Services Division, Taxi
Unit
101 Monroe Street, 5th Floor
Rockville, MD 20850
(240) 777-2227, 7433 (DPWT/TS), or 7170 (DPWT main number)
TDD: (240) 777-5869
transit.dpwt@montgomerycountymd.gov
The state's contact information is:
Maryland Public Service Commission
Transportation (Common Carrier Investigations) Division
William Donald Schaefer Tower
6 St. Paul Street, 16th Floor
Baltimore, MD 21202
(410) 767-8128 or 8000 (PSC main number)
FAX: (410) 333-6088
In addition, the WMATA (Washington Metropolitan Area Transit Commission) may be useful if you need to identify a Washington, D.C. carrier: (202) 331-1671 [source]
However, according to NBC4, the D.C. Taxi Commission can be reached at (202) 645-6005, and although this is listed as a complaints number, they might be able to help you identify the cab company.
In Arlington County, VA, the Licensing Division can be contacted at (703) 228-4258. In Fairfax County, VA, the Taxicab Hotline (aka the complaints line) at the Consumer Protection Division is (703) 324-5932.
I hope that this page has helped you find out which cab company operated the vehicle that caused you grief (or cheer, possibly). As far as I know, each cab in Maryland has a distinctive registration sequence and color.
For example, there are many cab companies in the area which operate white cabs, but only one that operates white cabs that are numbered in the one-thousand range (it's Regency Cab, in Montgomery County). The only company that operates white taxis in Prince George's County is Silver Cab, which is also known as Checker Cab, and all of their cabs have three digits, not four. There are no white cabs at all in Anne Arundel County nor in Howard County. (Baltimore County, Baltimore City, the Baltimore-Washington Airport, and a few other jurisdictions also happen to have white cabs.)
Back to the regularly scheduled babble.