Short answer. It comes from somewhere else. Section 8 states that the suspension of actions is governed by the provisions of the Civil Code and other laws, meaning this Rule does not itself supply the grounds or procedure — you have to look to those substantive laws instead.
What the law says
The suspension of actions shall be governed by the provisions of the Civil Code and other laws.
Rule 30, Section 8 — Suspension of actions. Read the full provision →
A deliberately short, referential provision
Rather than setting its own standard for when a civil action may be suspended, Section 8 simply points outward to the Civil Code and other laws as the governing source for that question. It functions as a cross-reference rather than a self-contained rule, telling the reader where to look instead of supplying the grounds for suspension itself. This is a fairly unusual structure within the Rules of Court, which generally set out their own standards directly rather than deferring wholesale to an entirely separate, outside body of law for the basic grounds themselves. The provision's brevity is itself deliberate: rather than attempting to enumerate every possible ground for suspension and risk the list becoming outdated or incomplete, the rule simply hands the question to whatever substantive law already governs it.
What this means in practice
A party seeking suspension of an action cannot rely on Rule 30 itself as authority for the request; they need to identify the specific Civil Code provision or other statute that actually authorizes suspension in their particular situation. Citing this section alone, without pointing to the underlying substantive basis, leaves the motion for suspension without the legal footing it actually needs to succeed. Common examples that parties invoke under this framework include a prejudicial question pending in a related criminal case, or another recognized ground drawn from the Civil Code's own provisions on when ordinary civil litigation may properly be paused pending resolution elsewhere. A motion that cites only Section 8, without identifying which specific outside provision actually authorizes the suspension being requested, gives the court nothing concrete to rule on and invites denial for lack of legal basis.
Why the Rules of Court defers here
Grounds for suspending an action are treated as matters of substantive law rather than procedure, so this procedural rule steps aside and simply defers to wherever that substantive basis is actually found in the law. This reflects a broader, recurring principle in how the Rules of Court are structured: procedural rules govern how a case moves, while substantive law continues to govern the underlying rights, remedies, and legal consequences actually available to the parties in the dispute. Keeping that line clear also means changes to the Civil Code or other statutes governing suspension take effect without requiring any corresponding amendment to Rule 30 itself, since the rule never froze the substantive grounds into its own procedural text.