A litigant is not estopped by laches from assailing the jurisdiction of a trial court over the subject matter for the first time on appeal if the challenge is made without unreasonable delay and the factual circumstances do not mirror the exceptional scenario of Tijam v. Sibonghanoy, where the jurisdictional challenge was raised only after almost 15 years. The general rule that a court's lack of jurisdiction may be raised at any stage of the proceedings, even on appeal, prevails, as jurisdiction is conferred by law and cannot be vested by consent or waiver of the parties.

The case arose from a criminal information for reckless imprudence resulting in homicide filed against the petitioner, Venancio Figueroa y Cervantes. The core issue that reached the Supreme Court revolved around whether the petitioner was barred by estoppel by laches from questioning the jurisdiction of the Regional Trial Court (RTC) which tried and convicted him, given that he only raised the jurisdictional challenge for the first time during his appeal to the Court of Appeals.

• On July 8, 1994, an information for reckless imprudence resulting in homicide was filed against petitioner Venancio Figueroa y Cervantes before the Regional Trial Court (RTC) of Bulacan, Branch 18.
• The imposable penalty for the crime charged (prision correccional in its medium and maximum periods, or 2 years, 4 months, and 1 day to 6 years) placed it under the exclusive original jurisdiction of Municipal Trial Courts (MTCs) pursuant to Section 32(2) of Batas Pambansa Blg. 129, as amended by Republic Act No. 7691, which was in effect at the time of the filing of the information.
• Trial on the merits ensued in the RTC, and on August 19, 1998, the RTC convicted the petitioner.
• The petitioner actively participated in the trial for four years without raising the issue of the RTC's jurisdiction.
• In his appeal before the Court of Appeals (CA), the petitioner, for the first time, questioned the RTC's jurisdiction over the case.
• The CA, in its decision dated February 28, 2001, affirmed the conviction, ruling that the petitioner was estopped by laches from assailing the RTC's jurisdiction due to his active participation in the trial and belated challenge.

• The RTC lacked jurisdiction over the subject matter of the case, as the imposable penalty for reckless imprudence resulting in homicide fell within the exclusive original jurisdiction of the MTCs under B.P. Blg. 129, as amended by R.A. No. 7691.
• Lack of jurisdiction over the subject matter may be raised at any time, even for the first time on appeal.
• The doctrine of estoppel by laches, as laid down in Tijam v. Sibonghanoy, does not apply because the issue of jurisdiction was raised immediately upon appeal to the CA, and there was no undue delay comparable to the nearly 15 years in Tijam.
• Active participation in a trial initiated by the public prosecutor in the wrong court does not amount to estoppel.

• While acknowledging the RTC's lack of jurisdiction, the People of the Philippines, through the Solicitor General, argued that the petitioner was precluded by the principle of estoppel by laches from questioning the RTC's jurisdiction.
• The petitioner actively participated in the trial for four years without ever raising the jurisdictional infirmity.
• The petitioner only questioned the RTC's jurisdiction after an adverse decision was rendered against him, which constitutes a belated attack.

• Whether the petitioner is estopped by laches from assailing the jurisdiction of the Regional Trial Court for the first time on appeal before the Court of Appeals.
• Whether the Regional Trial Court had jurisdiction over the criminal case for reckless imprudence resulting in homicide.

• The petition for review on certiorari was GRANTED. Criminal Case No. 2235-M-94 was DISMISSED without prejudice.
• The RTC of Bulacan did not have jurisdiction over Criminal Case No. 2235-M-94. At the time the criminal information was filed, Section 32(2) of B.P. Blg. 129, as amended by R.A. No. 7691, conferred exclusive original jurisdiction over offenses punishable with imprisonment not exceeding six years (like the one charged) to Metropolitan Trial Courts, Municipal Trial Courts, and Municipal Circuit Trial Courts.
• The petitioner is not estopped by laches from assailing the jurisdiction of the RTC. The Court clarified that the ruling in Tijam v. Sibonghanoy regarding estoppel by laches on the issue of jurisdiction is an exception to the general rule that jurisdiction may be raised at any stage. This exception applies only in cases with factual milieus analogous to Tijam, where the jurisdictional challenge was made after an unreasonable and unexplained length of time (almost 15 years).
• Raising the issue of lack of jurisdiction on appeal before the appellate court, as the petitioner did, does not constitute an unreasonable delay that would trigger estoppel by laches. No considerable period had elapsed for laches to attach.
• The general rule remains that a court's lack of jurisdiction over the subject matter may be raised at any stage of the proceedings, even on appeal, as jurisdiction is conferred by law and not by consent or waiver of the parties.
• A judgment rendered by a court without jurisdiction over the subject matter is null and void.

• Jurisdiction over the Subject Matter — Jurisdiction is the authority of a court to hear and decide a case, and it is conferred by law in force at the time of the institution of the action. It cannot be conferred by consent or agreement of the parties, nor waived by any act or omission. The Court reiterated that the RTC lacked jurisdiction as per B.P. Blg. 129, as amended by R.A. No. 7691.
• Estoppel by Laches — Laches is the failure or neglect, for an unreasonable and unexplained length of time, to do that which, by exercising due diligence, could or should have been done earlier, warranting a presumption that the party entitled to assert a right has abandoned or declined to assert it. The Court held that estoppel by laches to bar a litigant from asserting a court's lack of jurisdiction only supervenes in exceptional cases similar to Tijam v. Sibonghanoy, where the delay in raising jurisdiction was nearly 15 years. In this case, raising the issue on appeal for the first time was not deemed an unreasonable delay constituting laches.
• Void Judgment — A judgment rendered by a court without jurisdiction over the subject matter is void. The Court stated that no laches will even attach when the judgment is null and void for want of jurisdiction, and such proceedings are susceptible to direct and collateral attacks.
• General Rule on Raising Lack of Jurisdiction — A court's lack of jurisdiction may be raised at any stage of the proceedings, even on appeal. The Court affirmed this general rule, stating that the Sibonghanoy doctrine is the exception, not the rule.

• "The general rule should, however, be, as it has always been, that the issue of jurisdiction may be raised at any stage of the proceedings, even on appeal, and is not lost by waiver or by estoppel. Estoppel by laches, to bar a litigant from asserting the court's absence or lack of jurisdiction, only supervenes in exceptional cases similar to the factual milieu of Tijam v. Sibonghanoy."
• "Indeed, the fact that a person attempts to invoke unauthorized jurisdiction of a court does not estop him from thereafter challenging its jurisdiction over the subject matter, since such jurisdiction must arise by law and not by mere consent of the parties. This is especially true where the person seeking to invoke unauthorized jurisdiction of the court does not thereby secure any advantage or the adverse party does not suffer any harm."
• "We note at this point that estoppel, being in the nature of a forfeiture, is not favored by law. It is to be applied rarely--only from necessity, and only in extraordinary circumstances. The doctrine must be applied with great care and the equity must be strong in its favor. When misapplied, the doctrine of estoppel may be a most effective weapon for the accomplishment of injustice."
• "A judgment rendered without jurisdiction over the subject matter is void. Hence, the Revised Rules of Court provides for remedies in attacking judgments rendered by courts or tribunals that have no jurisdiction over the concerned cases. No laches will even attach when the judgment is null and void for want of jurisdiction."

• Tijam v. Sibonghanoy (131 Phil. 556 (1968)) — Referenced extensively as the landmark case establishing the doctrine of estoppel by laches concerning jurisdictional challenges. The Court distinguished the present case from Sibonghanoy due to the much shorter period before jurisdiction was questioned (on appeal vs. almost 15 years). Sibonghanoy is an exception to the general rule.
• U.S. v. De La Santa (9 Phil. 22 (1907)) — Cited for the early declaration that lack of jurisdiction over the subject matter is fatal and can be objected to at any stage, and that jurisdiction is given only by law.
• People v. Casiano (111 Phil. 73 (1961)) — Cited for explaining that if a lower court had no jurisdiction, parties are not barred on appeal from assailing such jurisdiction, as it must exist as a matter of law and cannot be conferred by consent or estoppel.
• Calimlim v. Ramirez (204 Phil. 25 (1982)) — Cited as a case that cautioned against the indiscriminate application of the Sibonghanoy doctrine, emphasizing that Sibonghanoy was an exceptional circumstance and that the general rule is the non-waivability of objections to jurisdiction. The present case followed the reasoning in Calimlim.
• Metromedia Times Corporation v. Pastorin (G.R. No. 154295, July 29, 2005, 465 SCRA 320) — Cited as a case where the Court stated that the ruling in Sibonghanoy stands as an exception, rather than the general rule, and a party was not estopped from assailing jurisdiction on appeal.
• Francel Realty Corporation v. Sycip (G.R. No. 154684, September 8, 2005, 469 SCRA 424) — Referenced for clarifying that Sibonghanoy applies only to exceptional circumstances where laches is clearly present (i.e., jurisdiction raised so belatedly as to warrant presumption of abandonment).
• Mangaliag v. Catubig-Pastoral (G.R. No. 143951, October 25, 2005, 474 SCRA 153) — Cited for reiterating that estoppel by active participation is an exception (as in Sibonghanoy) and not the general rule, and that Sibonghanoy involved a 15-year delay.
• Regalado v. Go (G.R. No. 167988, February 6, 2007, 514 SCRA 616) — Cited for emphasizing that for the Sibonghanoy doctrine to apply, laches must be clearly present, meaning jurisdiction was raised so belatedly as to presume abandonment.
• Heirs of Julian Dela Cruz and Leonora Talaro v. Heirs of Alberto Cruz (G.R. No. 162890, November 22, 2005, 475 SCRA 743) — Cited for the principle that jurisdiction over the subject matter is determined by material allegations and relief prayed for, conferred by law, not by consent/waiver, and estoppel does not confer jurisdiction. Proceedings without jurisdiction are null and void.

• Batas Pambansa Blg. 129, Section 32(2) (as amended by Republic Act No. 7691) — This provision on the Jurisdiction of Metropolitan Trial Courts, Municipal Trial Courts, and Municipal Circuit Trial Courts in Criminal Cases was central to the ruling. It states that these courts have exclusive original jurisdiction over all offenses punishable with imprisonment not exceeding six years. The Court applied this to determine that the RTC lacked jurisdiction over the petitioner's case.
• Revised Penal Code, Art. 365 — Mentioned in footnote 6 as the article defining and penalizing the crime of reckless imprudence resulting in homicide, for which the petitioner was charged. The imposable penalty under this article, in conjunction with B.P. Blg. 129, determined the proper court jurisdiction.