(General legal information; not legal advice.)

1) Set the terms straight: “annulment” vs. “nullity,” and why the Supreme Court even comes up

In everyday Philippine usage, people say “annulment” for any court case that ends a marriage. Legally, there are two different actions under the Family Code:

Annulment of a voidable marriage (Family Code, Article 45) The marriage is valid until annulled (e.g., lack of parental consent in certain cases, fraud, force/intimidation, impotence, serious STD, psychological incapacity is not here—see below).
Declaration of absolute nullity of a void marriage (Family Code, Articles 35, 36, 37, 38, etc.) The marriage is void from the beginning (e.g., lack of essential/requisite formalities, bigamous marriages, incestuous marriages, psychological incapacity under Art. 36, etc.).

Most cases reach the Supreme Court only if they are appealed after a trial court decision and usually after review by the Court of Appeals (CA).

2) Where annulment/nullity cases are filed and how they move

2.1 Trial court: the Family Court (RTC)

Cases for annulment/nullity are filed with the Regional Trial Court designated as a Family Court (or the RTC acting as such where no Family Court exists), following the Supreme Court’s special rules on procedure (A.M. No. 02-11-10-SC).

Key features in trial court practice (high-level):

Verified petition, required attachments, and payment of fees.
Service of summons and participation of the respondent (or declaration of default procedures in some circumstances, subject to strict rules).
Mandatory involvement of the State through the public prosecutor (and typically the Office of the Solicitor General (OSG) on behalf of the Republic), primarily to prevent collusion and ensure the case isn’t a “friendly” dissolution of marriage.
Pre-trial, trial, then decision.
If granted, the decision must be properly recorded/registered with the civil registry for effects on civil status and (when applicable) property relations.

2.2 Appeals: CA first, then SC

From the RTC/Family Court to the CA: generally by ordinary appeal (Rules of Court, Rule 41, as adopted by the special rule).
From the CA to the Supreme Court: generally by Petition for Review on Certiorari under Rule 45 (typically limited to questions of law), or exceptionally via Rule 65 (grave abuse of discretion) under strict conditions.

This matters because the “brief” usually lives in the CA stage, while the SC stage is more often driven by a petition, comment, reply, and memoranda rather than the classic “appellant’s brief/appellee’s brief” structure.

3) What people mean by “appearance” in the Supreme Court

3.1 “Entry of appearance” (or notice of appearance) is about counsel, not a courtroom appearance

In Philippine appellate practice, “appearance” commonly means a lawyer formally notifying the court that they represent a party. In the Supreme Court, counsel typically “enters appearance” by:

Signing and filing the first pleading they submit (petition/comment), and/or
Filing a formal entry/notice of appearance, especially when replacing prior counsel.

This is not the same as an in-person hearing. The Supreme Court often resolves cases on the pleadings without oral argument, unless the Court specifically sets one (which is uncommon and reserved for issues the Court chooses to ventilate in open court).

3.2 Personal appearance of parties is usually not the Supreme Court’s focus

At the trial court level, the petitioner’s testimony and witness presentation can be central. At the Supreme Court level, the case is usually about whether the lower courts committed reversible legal error—so the emphasis is on the record and legal arguments, not live testimony.

4) What “brief” means—and where it fits in annulment-related litigation

4.1 The classic “brief” is a Court of Appeals requirement

In ordinary appeals to the CA, the appealing party files an Appellant’s Brief, then the other side files an Appellee’s Brief, and sometimes a Reply Brief follows. These are structured documents with required parts (statement of facts, issues, arguments, citations to record, etc.).

4.2 In the Supreme Court, you often file “memoranda” instead of classic briefs

When a case reaches the Supreme Court (commonly via Rule 45), the typical flow is:

Petition (and its annexes/record references)
The Court may require a Comment
The petitioner may file a Reply
If the Court gives due course, it may require the parties to submit Memoranda (sometimes informally called “briefs” by laypeople)

So, if someone says “Supreme Court brief,” they may actually mean:

The petition itself (Rule 45), or
The required memorandum after due course, or
Less commonly, a Court-ordered brief in a special posture.

5) The “90-day period” people associate with annulment/Supreme Court—what it is and what it is not

5.1 The Constitution’s decision periods: where “90 days” really belongs

The Philippine Constitution sets timeframes for courts to decide cases from the time a case is submitted for decision:

Lower courts (including RTC/Family Courts): 3 months (commonly described as 90 days)
Court of Appeals (and other collegiate courts below the SC): 12 months
Supreme Court: 24 months

So the 90-day period is not the Supreme Court’s decision period; it is the trial court period (and generally “3 months” by constitutional text), counted from submission for decision, not from filing of the petition.

5.2 “90 days” is not a guaranteed timeline for an annulment case

Annulment/nullity cases are document-heavy and step-driven (service, prosecutor/OSG participation, pre-trial, trial settings, receipt of transcripts, submissions of memoranda, etc.). Even if the constitutional “3 months from submission” is the benchmark for a trial court’s decision-writing period, getting to “submission for decision” can take much longer, and delays can occur due to:

Difficulty serving the respondent,
Resettings and crowded dockets,
Completion of testimony and documentary requirements,
Court-ordered submissions (memoranda, formal offers, comments),
Motions that interrupt the flow,
Appeals.

5.3 The Supreme Court is not bound by a “90-day to decide” rule

If the question is: “Does the Supreme Court have to decide annulment cases within 90 days?” — the general constitutional benchmark for the Supreme Court is 24 months from submission for decision, not 90 days.

6) The “90-day period” that may show up as a deadline to file something (and why it’s not universal)

People sometimes hear “90 days” as a filing deadline. In actual practice, appellate deadlines are typically shorter and depend on the court and the pleading. Examples of timeframes that exist in the Rules of Court or typical court orders include:

Time to file a notice of appeal (trial to CA) is commonly days/weeks, not months.
Time to file a Rule 45 petition is also commonly days/weeks, with possible extensions.
The Supreme Court may set deadlines for comments or memoranda that vary by order.

A “90-day” number can appear if:

A party is granted multiple extensions that cumulatively approach that length; or
Someone is referring loosely to “three months” in a constitutional context; or
They are mixing up different court timelines.

Because the Supreme Court can tailor deadlines by resolution, there is no single universal “90-day brief period” that automatically applies to every annulment-related case in the Supreme Court.

7) What the Republic (OSG/prosecutor) does on appeal and why it affects pleadings

In annulment/nullity, the Republic’s participation is structural:

At trial: the prosecutor checks for collusion and may participate to ensure the case isn’t a simulated dissolution.
On appeal: the Republic is commonly represented by the OSG (or the OSG supervises/deputizes), defending the State’s interest in the marriage as a social institution and in the integrity of civil status records.

Practically, this means:

Even if the respondent spouse is absent or does not participate, the Republic may still actively oppose the petition or the appeal.
Pleading requirements and service rules are strictly enforced because civil status and public interest are involved.

8) Supreme Court review in annulment/nullity: what issues typically matter

At the Supreme Court level, the Court typically focuses on legal correctness, not re-trying facts. Common themes include:

Whether the lower courts applied the proper legal standard (e.g., in psychological incapacity under Article 36, the legal test and sufficiency of evidence are frequent points of dispute).
Whether procedural safeguards were observed (due process, service, prosecutor/OSG participation, collusion safeguards).
Whether the decision is supported by the record in a way that meets the governing jurisprudential framework.

Because Rule 45 is generally for questions of law, attempts to re-litigate pure factual findings are usually disfavored, subject to recognized exceptions.

9) Practical anatomy of Supreme Court pleadings in this context (conceptual guide)

While the exact flow depends on the Court’s resolutions, a typical Rule 45 posture looks like:

Petition for Review on Certiorari (Rule 45)
- Raises questions of law; attaches CA decision/resolution and relevant portions of the record as required.
- Counsel’s appearance is reflected in the petition/entry of appearance.
Comment (if required)
- Often filed by the adverse party and/or the OSG for the Republic.
Reply (sometimes allowed/required)
Memoranda (if the Court gives due course and orders memoranda)
- This is where many people colloquially say “brief,” even though the SC document is often styled “Memorandum.”
Decision/Resolution
- The Supreme Court may deny the petition outright (common), or give due course and decide on the merits.

10) Key takeaways (Philippine context)

“Appearance” at the Supreme Court usually means counsel’s formal representation on record, not an in-person courtroom appearance.
“Brief” is most classically a Court of Appeals concept; in the Supreme Court the functional equivalent is often a petition and later memoranda, depending on the Court’s orders.
The “90-day period” is commonly (and correctly) associated with the trial courts’ constitutional decision period measured from submission for decision, not a Supreme Court 90-day rule and not a guaranteed timeline for annulment cases.
Annulment/nullity litigation is public-interest–laden; the Republic (OSG/prosecutor) plays an institutional role that affects procedure and often the trajectory on appeal.