Is Congress prohibited from reducing the appropriations of Constitutional Commissions below the amount appropriated for them for the previous year? How about the Judiciary?

With respect to the Judiciary, Art. VIII, Section 3 of the Constitution explicitly provides:

Section 3. The Judiciary shall enjoy fiscal autonomy. Appropriations for the Judiciary may not be reduced by the legislature below the amount appropriated for the previous year and, after approval, shall be automatically and regularly released.

On the other hand, in the parallel provision granting fiscal autonomy to Constitutional Commissions, a similar proscription against the reduction of appropriations below the amount for the previous year is clearly absent. Article IX (A), Section 5 merely states:

Section 5. The Commission shall enjoy fiscal autonomy. Their approved annual appropriations shall be automatically and regularly released.

The plain implication of the omission of the provision proscribing such reduction of appropriations below that for the previous year is that Congress is not prohibited from reducing the appropriations of Constitutional Commissions below the amount appropriated for them for the previous year. (Civil Service Commission vs. DBM, G.R. No. 158791, July 22, 2005)