CA Prob Code Section 18100

With respect to a third person dealing with a trustee or assisting a trustee in the conduct of a transaction, if the third person acts in good faith and for a valuable consideration and without actual knowledge that the trustee is exceeding the trustee’s powers or improperly exercising them:

(a)

The third person is not bound to inquire whether the trustee has power to act or is properly exercising a power and may assume without inquiry the existence of a trust power and its proper exercise.

(b)

The third person is fully protected in dealing with or assisting the trustee just as if the trustee has and is properly exercising the power the trustee purports to exercise.