WHAT INTEREST IS NEEDED IF ONE SUES AS A "CITIZEN"?
When suing as a citizen, the interest of the petitioner assailing the constitutionality of a statute must be direct and personal. He must be able to show, not only that the law or any government act is invalid, but also that he sustained or is in imminent danger of sustaining some direct injury as a result of its enforcement, and not merely that he suffers thereby in some indefinite way. It must appear that the person complaining has been or is about to be denied some right or privilege to which he is lawfully entitled or that he is about to be subjected to some burdens or penalties by reason of the statute or act complained of.77 In fine, when the proceeding involves the assertion of a public right,78 the mere fact that he is a citizen satisfies the requirement of personal interest.
WHAT ABOUT THE SUIT AS A "TAXPAYER"?
In the case of a taxpayer, he is allowed to sue where there is a claim that public funds are illegally disbursed, or that public money is being deflected to any improper purpose, or that there is a wastage of public funds through the enforcement of an invalid or unconstitutional law.79 Before he can invoke the power of judicial review, however, he must specifically prove that he has sufficient interest in preventing the illegal expenditure of money raised by taxation and that he would sustain a direct injury as a result of the enforcement of the questioned statute or contract. It is not sufficient that he has merely a general interest common to all members of the public.80
At all events, courts are vested with discretion as to whether or not a taxpayer's suit should be entertained.81 This Court opts to grant standing to most of the petitioners, given their allegation that any impending transmittal to the Senate of the Articles of Impeachment and the ensuing trial of the Chief Justice will necessarily involve the expenditure of public funds.
WHEN IS A LEGISLATOR ALLOWED TO SUE TO QUESTION OF CONSTITUTIONALITY?
As for a legislator, he is allowed to sue to question the validity of any official action which he claims infringes his prerogatives as a legislator.82 Indeed, a member of the House of Representatives has standing to maintain inviolate the prerogatives, powers and privileges vested by the Constitution in his office.83
While an association has legal personality to represent its members,84 especially when it is composed of substantial taxpayers and the outcome will affect their vital interests,85 the mere invocation by the Integrated Bar of the Philippines or any member of the legal profession of the duty to preserve the rule of law and nothing more, although undoubtedly true, does not suffice to clothe it with standing. Its interest is too general. It is shared by other groups and the whole citizenry. However, a reading of the petitions shows that it has advanced constitutional issues which deserve the attention of this Court in view of their seriousness, novelty and weight as precedents.86 It, therefore, behooves this Court to relax the rules on standing and to resolve the issues presented by it.