Looks like the Constitutional "teacher" forgot about this.
The courts have consistently held that executive privilege is not absolute and can be overcome by an adequate showing of need. This is a flexible standard and does not lend itself to clear predictions about whether a particular assertion of executive privilege will be upheld, but the courts have provided some guidelines to govern claims of executive privilege. The Supreme Court held in United States v. Nixon, for example, that a claim of executive privilege will normally be defeated when the privileged information is needed to provide evidence in a criminal trialalthough the strong presumption against revealing information that would jeopardize national security would control even in this instance.
Executive Privilege 101
The courts have consistently held that executive privilege is not absolute and can be overcome by an adequate showing of need. This is a flexible standard and does not lend itself to clear predictions about whether a particular assertion of executive privilege will be upheld, but the courts have provided some guidelines to govern claims of executive privilege. The Supreme Court held in United States v. Nixon, for example, that a claim of executive privilege will normally be defeated when the privileged information is needed to provide evidence in a criminal trialalthough the strong presumption against revealing information that would jeopardize national security would control even in this instance.
Executive Privilege 101