CIR's power to interpret tax laws, decide tax cases

Section 4 of the 1997 National Internal Revenue Code (NIRC) confers upon the Commissioner of Internal Revenue (CIR) both: (a) the power to interpret tax laws in the exercise of her quasi-legislative function; and (b) the power to decide tax cases in the exercise of her quasi-judicial function. It also delineates the jurisdictional authority to review the validity of the CIR's exercise of the said powers, thus:
SEC. 4. Power of the Commissioner to Interpret Tax Laws and to Decide Tax Cases. - The power to interpret the provisions of this Code and other tax laws shall be under the exclusive and original jurisdiction of the Commissioner, subject to review by the Secretary of Finance.

The power to decide disputed assessments, refunds of internal revenue taxes, fees or other charges, penalties imposed in relation thereto, or other matters arising under this Code or other laws or portions thereof administered by the Bureau of Internal Revenue is vested in the Commissioner, subject to the exclusive appellate jurisdiction of the Court of Tax Appeals. (Emphases and underscoring supplied)