All horse drawn vehicles must have brakes
Each horse-drawn vehicle engaged in carrying loads on the streets and highways of the District shall be equipped with an effective brake.
Each horse-drawn vehicle engaged in carrying loads on the streets and highways of the District shall be equipped with an effective brake.
This is part of the Public Health (Control of Disease) Act 1984, sections 33 and 34: Public Conveyances. An interesting discussion regarding this law (and a few others) can be found here.