united-states
Willful blindness, also known as conscious avoidance, is a
judicially-made doctrine that expands the definition of knowledge to
include closing one's eyes to the high probability a fact exists.
While the doctrine originated in the context of drug trafficking
cases, it has since been expanded to a wide array of prosecutions and
is increasingly used in white collar cases.
(Source)
The definition above, from the National Association of Criminal Defense Lawyers, however, is less apt than the one below from Wikipedia which better captures the essence of it:
In law, willful ignorance is when a person seeks to avoid civil or
criminal liability for a wrongful act by intentionally keeping
themselves unaware of facts that would render them liable or
implicated. In United States v. Jewell, [532 F.2d 697 (9th Cir.
1976),] the court held that proof of willful ignorance satisfied the
requirement of knowledge as to criminal possession and importation of
drugs.
The concept is also applied to situations in which people
intentionally turn their attention away from an ethical problem that
is believed to be important by those using the phrase (for instance,
because the problem is too disturbing for people to want it dominating
their thoughts, or from the knowledge that solving the problem would
require extensive effort).
Terminology
Willful ignorance is sometimes called willful blindness, contrived
ignorance, conscious avoidance, intentional ignorance, or Nelsonian
knowledge.
The jury instruction for willful blindness is sometimes called the
"ostrich instruction".
(Wikipedia)
While there might be a distinction between federal law in some circumstances and the law of a particular state with regard to a particular matter, in general, willful blindness is a doctrine invoked in both federal and state courts in both civil and criminal cases.
For example, in civil fraud cases in most state courts, willful blindness can substitute for the requirement that the person committing the fraud has knowledge that a statement made in fraudulent.