The mandatory drug testing requirement for candidates for public office (Sec. 36(g) of RA 9165) is unconstitutional because it imposes an additional qualification not found in the Constitution. Mandatory drug testing for persons accused of crimes (Sec. 36(f)) is also unconstitutional as it violates the right to privacy and the right against self-incrimination. However, mandatory random drug testing for students (Sec. 36(c)) and employees (Sec. 36(d)) is constitutional, being a reasonable exercise of the State's police power and, in the case of students, within the schools' in loco parentis authority, and for employees, a reasonable regulation for workplace safety.

Republic Act No. 9165, the Comprehensive Dangerous Drugs Act of 2002, was enacted to intensify the government's campaign against dangerous drugs. Section 36 of this Act mandated drug testing for various sectors of society. These provisions prompted challenges from different petitioners, questioning their validity on several constitutional grounds, leading to these consolidated petitions before the Supreme Court.

• Republic Act No. 9165 (Comprehensive Dangerous Drugs Act of 2002) contains Section 36, which mandates authorized drug testing for: (c) Students of secondary and tertiary schools; (d) Officers and employees of public and private offices; (f) All persons charged before the prosecutor's office with a criminal offense having an imposable penalty of imprisonment of not less than six (6) years and one (1) day; and (g) All candidates for public office.
• The Commission on Elections (COMELEC) issued Resolution No. 6486 on December 23, 2003, prescribing rules for mandatory drug testing of candidates for public office for the May 10, 2004 elections, implementing Sec. 36(g) of RA 9165.
• Petitioner Aquilino Q. Pimentel, Jr., a senator and candidate for re-election, challenged Sec. 36(g) of RA 9165 and COMELEC Resolution No. 6486, arguing they impose an additional qualification for senators beyond those in the Constitution.
• Petitioner Social Justice Society (SJS), a registered political party, challenged paragraphs (c), (d), (f), and (g) of Sec. 36 of RA 9165, arguing they constitute undue delegation of legislative power, violate the equal protection clause, and infringe on the right against unreasonable searches.
• Petitioner Atty. Manuel J. Laserna, Jr., as a citizen and taxpayer, challenged paragraphs (c), (d), (f), and (g) of Sec. 36 of RA 9165, arguing they infringe on the rights to privacy, against unreasonable search and seizure, against self-incrimination, and violate due process and equal protection guarantees.

• Petitioner Pimentel argued that Sec. 36(g) of RA 9165 and COMELEC Resolution No. 6486 unconstitutionally add a qualification for senatorial candidates beyond the five qualifications enumerated in Article VI, Section 3 of the Constitution, which Congress or COMELEC cannot expand.
• Petitioner SJS argued that Sec. 36(c), (d), (f), and (g) of RA 9165 constitute undue delegation of legislative power by giving schools and employers unbridled discretion in drug testing, violate the equal protection clause by potentially being used for harassment, and breach the right against unreasonable searches.
• Petitioner Laserna argued that Sec. 36(c), (d), (f), and (g) of RA 9165 are unconstitutional for infringing on the constitutional rights to privacy, against unreasonable search and seizure, against self-incrimination, and for violating due process and equal protection guarantees.

• Respondents DDB and PDEA asserted that petitioners SJS and Laserna lacked locus standi as they failed to allege any specific incident violating their constitutional rights.
• Respondents generally defended the constitutionality of RA 9165, Section 36, as a valid exercise of police power aimed at curbing the drug menace.
• COMELEC, through Resolution No. 6486, argued that requiring candidates to undergo mandatory drug tests ensures that only those who can serve with utmost responsibility, integrity, loyalty, and efficiency would be elected, aligning with the constitutional principle of public accountability.

• Whether Sec. 36(g) of RA 9165 and COMELEC Resolution No. 6486 impose an additional qualification for candidates for senator, and if Congress can enact such a law.
• Whether paragraphs (c), (d), (f), and (g) of Sec. 36, RA 9165 are unconstitutional for violating the right to privacy, the right against unreasonable searches and seizure, the equal protection clause, or for constituting undue delegation of legislative power.
• Whether petitioners SJS and Laserna have locus standi to file their petitions.

• The Court granted Pimentel's petition, declaring Sec. 36(g) of RA 9165 and COMELEC Resolution No. 6486 unconstitutional. Congress cannot add qualifications for candidates for senator beyond those prescribed by the Constitution. The mandatory drug test for candidates effectively adds a pre-condition (being drug-free) not found in the Constitution.
• The Court partially granted the petitions of SJS and Laserna. Sec. 36(c) (students) and Sec. 36(d) (employees) of RA 9165 were declared constitutional. Random drug testing for students is justified by the school's in loco parentis role and the diminished privacy expectation of students, and for employees, it is a reasonable measure to ensure workplace safety and efficiency, with safeguards to protect privacy.
• Sec. 36(f) of RA 9165 (persons charged before the prosecutor's office) was declared unconstitutional. Mandatory drug testing for accused individuals cannot be random or suspicionless, as they are already singled out. It violates their right to privacy and right against self-incrimination, as it uses a medical test for criminal prosecution.
• The Court relaxed the rule on locus standi for SJS and Laserna due to the transcendental importance and paramount public interest involved in the enforcement of Sec. 36 of RA 9165. Pimentel, as a senator and candidate, possessed the requisite standing.
• The Court found no undue delegation of legislative power in Sec. 36(c) and (d) as the law and its IRR provide sufficient standards and safeguards for conducting the drug tests.

• Locus Standi — The right of a party to appear and be heard before a court. The Court relaxed this procedural rule for SJS and Laserna, citing transcendental importance and paramount public interest, allowing them to challenge the statute despite not showing direct personal injury.
• Judicial Review — The power of the courts to test the validity of governmental acts, including statutes, in light of constitutional provisions. The Court exercised this power to determine the constitutionality of Section 36 of RA 9165.
• Supremacy of the Constitution — The principle that the Constitution is the fundamental and paramount law to which all other laws must conform. This was applied to invalidate Sec. 36(g) as it conflicted with the constitutional qualifications for senators.
• Limitations on Legislative Power — The principle that Congress's power to legislate is not absolute but is subject to substantive constitutional limitations, such as those found in the Bill of Rights and specific provisions like qualifications for office. Applied to strike down Sec. 36(g) for exceeding constitutional limits on prescribing qualifications for senators.
• Right to Privacy — The right to be free from unwarranted exploitation of one's person or from intrusion into one's private activities. The Court balanced this right against compelling state interests. It was upheld for accused persons under Sec. 36(f) but found to be reasonably regulated for students and employees under Sec. 36(c) and (d).
• Right Against Unreasonable Searches and Seizures — The constitutional guarantee protecting individuals from arbitrary governmental intrusions. Drug testing was considered a search. Its reasonableness was evaluated by balancing the intrusion on individual privacy against the promotion of legitimate governmental interests. It was found unreasonable for accused persons (Sec. 36(f)) but reasonable for students (Sec. 36(c)) and employees (Sec. 36(d)) under specific conditions.
• In Loco Parentis — The legal doctrine under which an individual or institution assumes some parental responsibilities for a minor. This was invoked to justify random drug testing for students, as schools have a duty to safeguard their health and well-being.
• Undue Delegation of Legislative Power — The principle that legislative power, vested in Congress, cannot be delegated to other bodies without sufficient standards. The Court found no undue delegation in Sec. 36(c) and (d) as RA 9165 and its IRR provide guidelines for drug testing.
• Right Against Self-Incrimination — The constitutional protection ensuring that no person shall be compelled to be a witness against himself. This was a basis for declaring Sec. 36(f) unconstitutional, as mandatory drug testing for accused persons could force them to incriminate themselves.
• Reasonableness as Touchstone for Validity of Search — The principle that the validity of a warrantless search or intrusion is determined by its reasonableness, judged by balancing governmental intrusion on privacy against the promotion of compelling state interests. This was applied to uphold random drug testing for students and employees as reasonable.

• "The Constitution is the basic law to which all laws must conform; no act shall be valid if it conflicts with the Constitution. In the discharge of their defined functions, the three departments of government have no choice but to yield obedience to the commands of the Constitution. Whatever limits it imposes must be observed."
• "As the warrantless clause of Sec. 2, Art III of the Constitution is couched and as has been held, 'reasonableness' is the touchstone of the validity of a government search or intrusion."
• "To impose mandatory drug testing on the accused is a blatant attempt to harness a medical test as a tool for criminal prosecution, contrary to the stated objectives of RA 9165. Drug testing in this case would violate a persons' right to privacy guaranteed under Sec. 2, Art. III of the Constitution. Worse still, the accused persons are veritably forced to incriminate themselves."
• "The essence of privacy is the right to be left alone."

• Government v. Springer — Cited to illustrate the limits on legislative power, emphasizing that governmental departments are confined within the four walls of the constitution or charter.
• Vernonia School District 47J v. Acton — A US Supreme Court case upholding random drug testing for student-athletes. Referenced extensively to support the constitutionality of random drug testing for students in the Philippines, considering schools' in loco parentis role and students' reduced privacy expectations.
• Board of Education of Independent School District No. 92 of Pottawatomie County, et al. v. Earls, et al. — A US Supreme Court case upholding drug testing for students participating in extracurricular activities. Cited along with Vernonia to affirm the constitutionality of drug testing for students based on the school's custodial responsibility.
• Ople v. Torres — Referenced for the principle that an enabling law authorizing a search must be "narrowly drawn" or "narrowly focused." The Court found Sec. 36(d) of RA 9165, concerning employees, met this standard due to its specified purpose and safeguards.
• C. Camara v. Municipal Court — Cited for the difficulty in translating the abstract prohibition against unreasonable searches and seizures into workable broad guidelines, and that the right to privacy yields to certain paramount public rights and defers to the state's police power.
• Dumlao v. COMELEC — Cited in relation to the requirement for an actual case or controversy for judicial review.
• Gonzales v. Narvasa — Cited for the elements of standing: actual or threatened injury, traceable to the challenged action, and likely to be redressed by a favorable action.
• Tatad v. Secretary of the Department of Energy — Cited for the relaxation of the rule on standing when the matter is of transcendental importance.
• Mutuc v. Commission on Elections — Cited for the principle that constitutional limits must be observed by all government departments.
• Skinner v. Railway Labor Executives Assn. — A US Supreme Court case cited in Vernonia, relevant to balancing government-mandated intrusion on privacy against compelling state interests in the context of drug testing.

• Republic Act No. 9165, Section 36 — The central provision under scrutiny, mandating drug testing for various groups. Its paragraphs (c), (d), (f), and (g) were specifically analyzed.
• Republic Act No. 9165, Section 2 — The policy-declaration portion of the Act, stating the objective to stamp out illegal drugs and safeguard citizens. Referenced to understand the legislative intent behind the drug testing provisions.
• Republic Act No. 9165, Sections 54 and 55 — Provisions on voluntary submission to treatment and exemption from criminal liability. Cited to show that the primary legislative intent for random testing of students/employees is not criminal prosecution.
• Republic Act No. 9165, Section 94 — Charges the Dangerous Drugs Board (DDB) to issue Implementing Rules and Regulations (IRR). Referenced to counter the argument of unbridled discretion given to schools and employers.
• 1987 Constitution, Article VI, Section 3 — Enumerates the qualifications for a Senator. This was the primary basis for declaring Sec. 36(g) of RA 9165 unconstitutional.
• 1987 Constitution, Article III, Section 1 — Due process and equal protection clause. Invoked by petitioners as violated by the mandatory drug testing.
• 1987 Constitution, Article III, Section 2 — Right against unreasonable searches and seizures. Central to the analysis of the constitutionality of mandatory drug testing, which is considered a form of search.
• 1987 Constitution, Article XI, Section 1 — Public office is a public trust; public officers must be accountable. Referenced by COMELEC to justify drug testing for candidates and by the Court to support reasonableness for government employees.
• COMELEC Resolution No. 6486 — Implementing rules for mandatory drug testing of candidates for the 2004 elections. Declared unconstitutional alongside Sec. 36(g) of RA 9165.
• DOH IRR Governing Licensing and Accreditation of Drug Laboratories, Section 7 [3], [10.3], [10.4] — Provisions regarding chain of custody, access to results, and confidentiality. Cited to show safeguards in the drug testing process for employees.