As described in A Night Out: Adam’s Morgan Style, Red Top informed us that Virginia law limits the number of passengers in a cab to four. Out of sheer boredom, I decided to look into the matter.
 
Virginia Code § 15.2-949, Shared ride taxi systems, etc.; nonprofit vanpools, states:

A “shared ride taxi system” means a transportation system which employs taxicab-type vehicles or other motor vehicles which can carry no more than six passengers.

I believe that the number of passengers is capped at six because most of the largest cabs (minivans, SUVs) are designed to seat seven, including the driver. This means that the person who spoke to us on the phone lied to us… or did she?
 
While the law caps the number of passengers at six, you cannot legally exceed the passenger limit of the vehicle. This means that if your cab is a Ford Crown Victoria*, you can only have four passengers because the car comfortably (legally) seats five^.

* The Ford Crown Vic is one of the most common, if not the most common taxi cab in the United States because of its durability, cost and performance. It has body-on-frame construction, which means that it’s more rugged than other cars, and it can be repaired after minor accidents without the need to straighten the chassis, which is why it is a popular fleet car despite having a gas-guzzling V8.

^ While the Crown Vic traditionally has a column-mounted gearshift, and a two-bench, six-passenger-seating layout, in most taxis, the capacity is five passengers because the taximeter and computer dispatch module are situated in the front seat, leaving room for only one passenger in addition to the driver.

According to a Red Top official, for practical purposes most of their fleet can only seat five people, which means only four passengers can ride. While they do have minivans, those cabs seem to be reserved for airports and hotels.

Interestingly enough, Arlington County Code (pdf) § 25-15, No. 4 states:

Drivers shall not permit more persons to be carried in a taxicab in the county at any one (1) time than the seating capacity of the taxicab (as rated by the automobile manufacturer) including the driver, children in arms excepted.

The reason I find this interesting is that a child in someone’s arms doesn’t count towards seating capacity, yet passengers under 16 years old and sitting anywhere in the vehicle are required to wear a seat belt that fits snuggly across chest (or breastbone, for children) and hips, or they must be secured in a car seat or booster seat based on the Virginia child seat guidelines, according to Virginia Codes §46.2-1094 through §46.2-1096. If they’re in your arms, they don’t have a seat belt, so they’re breaking a law.

Obviously, the Arlington County law doesn’t exempt people from the Virginia law, but it’s still interesting that they would leave that wording in the law. Also, how is it any different holding a child, and having an adult sit on your lap, if you want to get technical…

Anyway, Arlington County Code § 25-15, No. 6 states:

At no time shall more than two (2) persons, in addition to the driver, ride on the front seat of any taxicab, a child in arms excepted.

While most cabs don’t, some cabs do have the bench seat in the front, so this part of the law seems to make sense, with the exception of the children in arms phrasing again.

So, after looking into it, the Red Top dispatcher did not lie to us. For all intents and purposes, it is illegal to take more than four people in a cab, children in arms excepted. Ha!