"One who takes the wheel of a car has a responsibility to know the rules of the road. So it is with civil and criminal law in general: ignorance does not exonerate in instances of violation. A householder who throws rubbish over the fence onto the neighbor's roses cannot acceptably plead ignorance of the laws pertaining to another's property; nor is a landowner who sprays trees with a noxious chemical exempted from responsibility for any attendant, wider environmental damage simply because of avowed ignorance about the possible effects of insecticide. People engaging in such activities are expected to have a reasonable degree of knowledge about their consequences and implications. ..."