Short answer. Yes. Rule 42 requires you to submit, together with the petition, a certification under oath that you have not previously commenced any other action involving the same issues in the Supreme Court, the Court of Appeals, or any other tribunal or agency — this is the forum-shopping certification.
What the law says
The petitioner shall also submit together with the petition a certification under oath that he has not theretofore commenced any other action involving the same issues in the Supreme Court, the Court of Appeals or different divisions thereof, or any other tribunal or agency
Rule 42, Section 2 — Form and contents. Read the full provision →
What the certification must state
Rule 42, Section 2 requires it directly: the petitioner shall also submit together with the petition a certification under oath that he has not theretofore commenced any other action involving the same issues in the Supreme Court, the Court of Appeals or different divisions thereof, or any other tribunal or agency. This sworn statement — the anti-forum-shopping certification — has to accompany the petition itself, not follow later as an afterthought.
Disclosing a related case if one already exists
The rule does not simply ask you to swear that no other action exists; it also covers the situation where one does: if there is such other action or proceeding, he must state the status of the same. A related case elsewhere is not automatically disqualifying under this provision — the requirement is disclosure, telling the court exactly what that other action or proceeding is and where it currently stands.
A continuing duty to inform the court
The obligation does not end once the petition is filed. The rule requires that if he should thereafter learn that a similar action or proceeding has been filed or is pending before the Supreme Court, the Court of Appeals, or different divisions thereof, or any other tribunal or agency, he undertakes to promptly inform the aforesaid courts and other tribunal or agency thereof within five days therefrom. Learning of a similar case later triggers its own five-day reporting duty.
One requirement among several the petition must satisfy
The certification sits alongside other formal requirements Section 2 imposes on a Rule 42 petition — filing in seven legible copies, stating the parties' full names, indicating the material dates that show timely filing, and setting out the issues and errors being raised, supported by certified copies of the lower courts' judgments. The certification is a mandatory piece of that overall package, not an optional attachment, and omitting it or falsifying it can expose the petition to consequences separate from whatever issue the petition itself raises on the merits.