The phrase you are looking for is "plausible deniability." Plausible deniability refers to the ability of a person to deny knowledge or involvement in a particular action or situation because they deliberately chose not to know or find out about it. This concept is often used in situations where someone wants to distance themselves from potential negative consequences or legal ramifications.
By claiming plausible deniability, individuals may avoid accountability or legal repercussions by stating that they were unaware of certain information or actions that could incriminate them. It allows them to protect themselves from being implicated in something they may have indirectly been involved in or had knowledge of.
Plausible deniability is commonly discussed in the context of politics, business, and other situations where decision-makers might want to protect themselves from being held responsible for controversial or illicit actions taken by their subordinates or associates.