Black Letter Law
The black letter law refers to the basic standard elements for a particular field of law, which are generally known and free from doubt or dispute.
The phrase definitely refers to a distillation of the common law into general and accepted legal principles and is used commonly in the Australian legal system to mean well-established case law.
In common law, black letter legal doctrine is an informal term indicating the basic principles of law generally accepted by the courts and/or embodied in the statutes of a particular jurisdiciton.
Letter of the law is its actual implementation, thereby demonstrating that black letter law are those statutes, rules, acts, laws, provisions, etc. that are or have been written down, codified, or indicated somewhere in legal texts throughout history of specific state law.
This is often the case for many precedents that have been set in the common law. An example of such a state within the common law jurisdiction, and using the black letter legal doctrine is Canada. Being a monarchical state, with its roots invested in Colonial England, black letter law is that which is a term used to describe basic principles of law that are accepted by the majority of judges in most provinces and territories.
Contract, tort and land law are typical black letter law subjects, whereas administrative law, example, would be considered considerably less black letter.
Colour of Law
Color of is a legal term meaning "pretense or appearance of" some right; in other words, 'color of', as in 'color of law', means the thing colors (or adjusts) the law; however the adjustment made may either be lawful or it may merely appear to be lawful.
Color of law refers to an appearance of legal power to act but which may actually operate in violation of law. For example, though a police officer acts with the color of law authority to arrest someone, if such an arrest is made without probably cause the arrest may actually be in violation of law. In other words, just because something is done with the 'color of law', that does not mean that the action was actually lawful.