The line between oversight and direct involvement in the conduct of policy is perhaps crossed when the Congress passes or even introduces a resolution or legislation that gives specific direction to raise or lower interest rates and, especially, when such directions are accompanied by proposed legislation that would reduce the independence of the Federal Reserve.
The history of the past twenty years shows that members of the Congress do try to influence monetary policy, especially when the economy is performing poorly or when interest rates are high or rising, but that the Congress has rarely gone so far as to pass legislation to direct policy. In fact, such legislation has often been introduced, though rarely passed.