On  March 5, 1957, petitioner-appellee, Maria Natividad vda. de Tan,  filed  with the Court  of First Instance  of Manila a verified petition for mandamus seeking an order to  compel  the respondent-appellant  Veterans  Back  Pay Commission:  (1)  to declare deceased Lt.  Tan  Chiat Bee alias   Tan Lian  Lay, a   Chinese   national,  entitled  to backpay rights, privileges1, and prerogatives under Republic  Act No. 304, as amended by Republic Act No. 897; and (2)  to give due course to the claim  of  petitioner, as  the widow of the  said veterans,  by issuing to  her the corresponding backpay  certificate of indebtedness.

Respondent Commission filed its  answer  in  due time asserting  certain  special  and  affirmative defenses,   on the basis  of which,  the Commission unsuccessfully  moved to  dismiss the petition.

The parties  then  submitted  a   stipulation  of  facts herein-below reproduced:

"Come  now the petitioner  and respondent in the  above-entitled case through their respective counsel, and  to this Honorable Court respectfully agree and  stipulate that the following facts are true:

1. That  the petitioner is of legal  age, widow, and a resident of 400 Lallana, Tondo, Manila;  that the respondent is a  government instrumentality or agency, with offices in the City of Manila, Philippines,  duly vested with authority to implement the provisions of the Backpay Law, otherwise known as Republic Act  No. 897,  further amending  Republic Act No. 304;
   
2. That the petitioner  is the widow of  the late Lt.  Tan Chiat Bee alias Tan Lion Lay, a Chinese national, and a bonafide member of  the  1st  Regiment,  United States-Chinese  Volunteers  in  the Philippines;
   
3. That the United States-Chinese Volunteers in the Philippines is a guerrilla  organization duly  recognized  by the  Army of the United States and forming part and parcel  of the Philippine Army;
   
4. That Tan Chiat Bee alias Tan Lian  Lay died in the service on  April 4, 1945 in  the battle at Ipo Dam, Rizal  Province, Philippines;  he was  duly  recognized as a  guerrilla veteran and certified to  by  the  Armed Forces of  the  Philippines as  having  rendered meritorious  military services  during the Japanese  occupation;
   
5. That petitioner as the widow of the  said  recognized  deceased veteran,  filed an  application  for  back pay under the provisions of Republic Act No. 897, the resolution of the  Veterans Back  Pay Commission dated  November 19, 1953 and the letter of the  Veterans Back Pay Commission dated December 9,  1953;
   
6. That on June 18, 1955, the Secretary and Chief of Office Staff of  the Veterans Back' Pay Commission sent a  letter to General Vicente Lopez of the United States-Chinese  Volunteers in the Philippines apprising the  latter  that the  Commission has  reaffirmed its resolution granting the back pay  to  alien  members;
   
7. That the Adjutant, Armed Forces of the Philippines, has verified and certified that deceased veteran has rendered service as a recognized  guerrilla for  the  period  indicated in  his  (Adjutant's) indorsement  to  the  Chief,  Finance  Service Armed Forces of the Philippines;
   
8. That,  likewise,  the Chief of Finance  Service, Camp  Murphy, has computed  the backpay due  the petitioner and the same  was passed in audit by the  representatives of the Auditor General;
   
9. That  after due deliberation respondent revoked its  previous stands and ruled  that aliens  are not  entitled  to back pay;
   
10. That  on February 13, 1957, the respondent Veterans  Back Pay Commission, through its Secretary & Chief of  Office Staff, made a formal reply to the aforesaid claim of the  herein petitioner denying her request on the ground  that aliens are  not entitled to  backpay;
    
11. That  upon refusal  of the Veterans Back Pay Commission the petitioner brought the case direct to this Honorable Court by way of mandamus;
    
12. That petitioner and respondent admit  the existence and authenticity of the following  documents;
    Annex A-Resolution of  the  Veterans Back Pay dated November 19, 1953.
    Annex R-Letter dated  December 9, 1953.
    Annex C-Letter dated June 18, 1955.
    Annex D-Executive Order No. 21 dated October 28, 1944.
    Annex E-Executive Order No. 68 dated September 26, 1945.
    Annex F-Minutes of the Resolution of the Back Pay Commission regarding the opinion of the Secretary of Justice dated February 8, 1956.
    Annex G-Letter of  Back Pay Commission dated  February 26, 1954 to Secretary of Justice.
    Annex H-Opinion No. 213 series of  1956  bf  the  Secretary of Justice.
    Annex I-Reply of  Veterans Backpay Commission.
    Annex J-Explanatory note to  House Bill No. 1953.
    Annex K-Explanatory  note to Senate  Bill No. 10.
    Annex L-Explanatory note to  House Bill  No. 1228, now Republic Act No. 897.
    Annex M-Joint Resolution No. 5 of the First Congress of the Philippines.
    
13. That  the parties waive the presentation of further evidence;
    
14. That the respondents will file its memorandum within ten (10) days from August 1, 1957 and the petitioner may file her memorandum within ten (10) days from receipt of respondent's memorandum, after which the case is deemed submitted for decision. Manila, July 31, 1957."
    

Based on the foregoing, the lower court rendered judgment the  dispositive  portion of which, reads:

"Wherefore, the petition  is granted,  ordering respondent  Commission to give due  course to the claim  of  herein petitioner to the backpay to which her deceased husband was entitled  as  member of a duly recognized guerrilla  organization."

Against  the  decision, the respondent  instituted  this appeal averring once more, in  its  assignment of  errors, the special and affirmative  defenses  that the  petitioner failed to  exhaust available  administrative remedies; that the suit is, in  effect,  an  action to  enforce a money claim against the government without its  consent;  that mandamus will  not lie  to compel the exercise of a  discretionary function; and that Republic Act  Nos.  304  and 897  already referred to were never  intended  to  benefit aliens.

We find no  merit in  the  appeal.  As to the claim that mandamus is not the proper  remedy to correct the exercise  of discretion  of the  Commission, it may  well  be remembered that its  discretion is limited  to  the facts of the case,  i.e.,  in merely evaluating the evidence whether or not  claimant is a member of  a guerrilla force duly recognized by  the  United  States Army.,  Nowhere  in the law is the  respondent  Commission given the power to adjudicate  or determine rights after  such facts are established.  Having been satisfied that deceased Tan Chiat Bee  was an officer of  a duly recognized  guerrilla outfit, certified to by the Armed Forces of the Philippines, having served under the United States-Chinese Volunteers in the Philippines, a guerrilla unit recognized  by the  United States Army  and forming  part of the Philippine Army, it becomes the ministerial duty of the respondent to give due  course to his  widow's application.   (See  sections 1 and  6,  Republic Act 897.)   Note  that the Chief of the Finance Service, Camp  Murphy, has accepted the backpay due  the petitioner's husband  and the same was passed in audit by the representatives of the Auditor General.

It is insisted  by  the  respondent  Commission that aliens are  not included within the purview of the law.  We disagree.  The  law as contained  in Republic Act Nos. 304  and 897 is explicit enough, and it extends its benefits to members  of "guerrilla forces  duly recognized by the Army of the  United States." From the  plain and clear language thereof, we fail to see any indication that its operation  should be limited  to  citizens  of the  Philippines only, for all that is  required is that  the guerrilla unit  be  duly  recognized  by the  Army  of the  United States.  We are in  full accord  with  Opinion  No.  213, series of 1956,  of the  Secretary of Justice, which reads:

"Section 1 of the cited Act (Republic Act No. 304, as amended by Republic Act No. 897), otherwise known as the Back Pay Law, recognizes the rights to the backpay of members of "guerrilla forces duly recognized by the Army of the  United States, among others. A perusal of its provisions reveals nothing which may be construed to mean that only Filipino citizens are entitled to back pay thereunder. On the contrary, the statute  expressly includes within its coverage  "persons under contract with the Government  of the Commonwealth", which clause was construed by this  office to refer to "experts  and technical personnel employed  for highly specialized service" by the government  (Opinion  No. 137, s. 1953), a majority of whom were non-citizens.   Thus, in  Opinion  No. 30,  s.  1949, this office ruled that a civil service employee of the U.S.  Coast and  Geodetic Survey rendering service to the Philippine Government when war broke out on December 8, 1941, was entitled to back pay.

As  regards guerrillas, it seems clear that  all the  law requires is that they be "duly recognized by the  Army  of the  United States." Section 1 of the Back Pay Law, it is also noted,  enumerates those who are not entitled to its benefits; recognized guerrillas who were not Filipino citizens are not among those  expressly mentioned.  The maxim expressio unius est exclusio alterius, I think, finds application here.

Moreover,  Executive Order No. 21, dated October 28, 1944, expressly declared that,  Sections  22 (a) and  27 of  Commonwealth Act No.  1 to the contrary  notwithstanding,  "all persons of any nationality or citizenship, who  are actively serving in recognized military  forces in the Philippines, are thereby considered to be on active service in the Philippine  Army."

It  is  the  respondent's  main argument that it could not have been  the intention  of  Congress to extend its benefit to  aliens, as the  purpose of  the law was  "precisely to help  rehabilitate members  of the  Armed  Forces of the Philippines and recognized  guerrillas  by giving them the right to acquire public lands and public  property  by using the back pay certificate", and "it  is  fundamental  under the  Constitution  that  aliens except  American  citizens cannot  acquire  public lands or exploit our natural resources".  Respondent Commission  fails to  realize  that this  is  just one of the  various uses of  the  certificate; and  that it  may  also   be  utilized  for  the  payment of obligations  to the  Government or to any of its branches or  instrumentalities, i.e., taxes,  government  hospital  bills, etc.   (See Sec. 2,  Rep.  Act No. 897).

As further  observed by the lower court:

"It is one thing to be entitled to backpay and to receive acknowledgment therefor, and another thing to receive backpay certificates in accordance with the resolutions of the Commission and  to make use  of the same."

It was,  therefore, unreasonable  if not arbitrary  on the  part of respondent  Commission to deny petitioner's claim on this basis.

It is further  contended  by the  Commission  that the petitioner should have first exhausted her administrative remedies  by  appealing  to  the   President of  the  Philippines,  and  that  her failure  to do  so  is a bar  to her action in  court  (Montes  vs.  The  Civil  Service  Board of Appeals, 101 Phil., 490;  54  Off.  Gaz.   [7] 2174.  The respondent  Commission is  in  estoppel  to invoke  this rule, considering that in its resolution (Annex F of the Stipulation  of Facts)  reiterating its  obstinate refusal to abide by the  opinion of the  Secretary of  Justice,  who is the legal  adviser of the  Executive  Department, the Commission declared that

"The opinions promulgated by the Secretary of Justice are advisory in nature, which  may either be accepted  or ignored by  the  office seeking the opinion,  and any  aggrieved  party  has the court for recourse,"  (Annex F)

thereby  leading the  petitioner to  conclude that  only a final judicial  ruling in  her favor would  be accepted by the Commission.

Neither is  there substance in  the contention that the petition is, in effect,  a suit against the government without its  consent.   The relief prayed for is simply "the recognition of  the rights of the  petitioner-appellee" under the provisions of sections 1 and 2  of Republic Act No.  897, and consists  in  "directing  an  agency of the government to perform an act * * * it is bound to perform."   Republic Act Nos. 304 and  897  necessarily  embody state  consent to  an action  against the officers entrusted with the implementation  of said Acts  in  case of unjustified  refusal to recognize the rights of proper  applicants.

The decision appealed from  should be,  and  hereby  is, affirmed.   No costs.  So ordered.

Paras  C. J.,  Bengzon, Padilla, Montemayor,  Reyes,  A. Bautista  Angelo,  Labrador,  Concepcion,  and  Endencia, JJ., concur.