Basel II classified Legal risk as a subset of Operational Risk in 2003. There is no standard definition, but there are at least two primary/secondary definition sets in circulation.
Mcormick, R. 2004 Legal risk is the risk of loss to an institution which is primarily caused by:
(a) a defective transaction; or
(b) a claim (including a defense to a claim or a counterclaim) being made or some other event occurring which results in a liability for the institution or other loss (for example, as a result of the termination of a contract) or;
(c) failing to take appropriate measures to protect assets (for example, intellectual property) owned by the institution; or
(d) change in law.
The expenses of litigation of a company.
Legal risk is the risk of financial or reputational loss that can result from lack of awareness or misunderstanding of, ambiguity in, or reckless indifference to, the way law and regulation apply to your business, its relationships, processes, products and services.
The cost and loss of income caused by legal uncertainty, multiplied by possibility of the individual event or legal environment as a whole.
One of the most obvious legal risks of doing business not mentioned in the above definitions is the risk of arrest and prosecution.
All definitions contain more detail.