Filing a Petition for Leave to Appeal or Cassation in Criminal Proceedings

In this article we examine the procedure of petitioning for leave to appeal or cassation in criminal proceedings under Thai law, with particular attention to criminal cases in which the statute limits the right of appeal or cassation (so-called “cases barred from automatic appeal/cassation”). The discussion is tailored for defence practitioners, clients in criminal law, and for those looking for representation from a lead law firm in Bangkok, and aims to clarify when, how and by whom a petition for leave must be filed — together with key practical and strategic remarks.

By clarifying the procedural steps and strategic dimensions of the petition for leave, defence counsel can better protect their clients’ rights and avoid forfeiture of appellate rights due to mis-steps.

1. Introduction

In criminal litigation, especially when the verdict affects a person’s liberty, the opportunity to challenge a decision via appeal or cassation is a critical safeguard. However, in certain criminal cases in Thailand, the right to appeal or cassation is not automatic and may be conditioned upon applying for leave (i.e., obtaining permission) from the trial court or other competent judge. This article addresses the procedure for filing a petition for leave to appeal or cassation in criminal proceedings, why it matters, what the legal thresholds and practical considerations are, and how counsel should prepare the submission.

By advising their clients at an early stage about the necessity of this petition, a defence team associated with a lead law firm in Bangkok can strengthen its strategic posture and minimise procedural risk.

2. Legal framework for appeal and cassation in criminal cases in Thailand

2.1 Structure of the criminal appellate system

Under Thai criminal procedure, a convicted party (or in some cases the prosecution) may appeal a judgment of a court of first instance (Trial Court) to a Court of Appeal, and in appropriate cases further to the Supreme Court (or cassation court) of Thailand. ThaiLawOnline+2sherloc.unodc.org+2
In brief:

At first instance the court issues a judgment.
Within a set time-limit (commonly 30 days from reading of judgment) an appeal may be filed. ThaiLawOnline+1
For cassation (the highest level) the court will generally review only legal issues (errors of law, procedure, or serious injustice) rather than re-litigating facts. Siam Center Law Group+1

2.2 Cases requiring leave (permission) to appeal or cassation

Importantly, not all criminal cases automatically permit direct appeal or cassation. Some categories of case are subject to thresholds or limitations. For instance:

Some less-serious verdicts (such as imprisonment not exceeding a certain term) may limit the right of appeal/cassation unless leave is granted. thailawforum.com+1
The rationale is that the highest court must focus resources on cases raising significant issues of law, public interest, or systemic importance. Siam Center Law Group
Thus, a petition for leave to appeal or cassation in criminal proceedings becomes the gateway in eligible cases.

2.3 Why the limitation?

The limitation serves multiple purposes:

Ensures that the highest court (cassation level) deals with matters of legal significance rather than all judgments.
Optimises judicial resources and expedites finality in less complex cases.
Encourages proportionate access: where stakes (e.g., short sentences) are lower, the right to appeal may be curtailed.

3. When is a petition for leave required in criminal proceedings?

3.1 Typical scenarios

In practical terms a petition for leave may be required where:

The court of first instance issues a sentence of imprisonment not exceeding a relatively low threshold (e.g., imprisonment for not more than 2 or 3 years) and the law treats the decision as final unless leave is granted. thailawforum.com
The court of appeal affirms the lower court judgment almost entirely and the cassation court will review only if leave is granted.
The judgment does not raise a significant question of law or public interest and thus falls outside the automatic cassation route.

3.2 Consequences of failing to file the petition

If a petitioner (defendant or appellant) fails to file a petition for leave together with the appeal/cassation notice (where required) within the prescribed time-limit, the right to challenge the judgment may be lost. This is critical — a missed procedural step may irretrievably close the door on further review.

3.3 Legal authority and interpretation

While the criminal procedure code amendments have clarified the permission-based approach in civil cases, commentators recognise a parallel approach in criminal proceedings. Siam Center Law Group+1 Although explicit statutory provisions for criminal leave petitions in all scenarios may be less frequently emphasised, the doctrine and practice support the necessity of obtaining permission in limited cases. Practitioners must therefore assess whether leave is required in a given case.

4. Who has authority to grant leave in criminal proceedings?

4.1 Competent judge(s)

In the scenario of a petition for leave to appeal or cassation in criminal proceedings, the following categories of judge may grant permission:

A judge who sat in the panel that adjudicated the case (whether the trial judge or appeal judge).
A judge who signed the judgment.
A judge who entered a dissenting opinion in the case (where multiple judges heard the case).

If there are multiple judges, one judge’s permission is sufficient to authorise the appeal/cassation.

4.2 Practical tips

Identify precisely which judge(s) qualify under the categories above.
Ensure the petition names the judge(s) and cites the authority by which permission is sought.
Obtain the signed order or official endorsement of leave before proceeding to file the full appeal/cassation.

5. How to draft the petition for leave to appeal or cassation in criminal proceedings

5.1 Timing and mode of filing

The petition must be submitted together with the intended appeal or cassation document, not as a standalone motion after the appeal/cassation.
It must be filed within the time-limit prescribed by law (commonly within 30 days from the reading of the judgment) unless the statute or court grants extension. ThaiLawOnline
If the petition is not included with the appeal, the appeal/cassation may be rejected on procedural grounds.

5.2 Structure of the petition

A well-drafted petition for leave should include the following elements:

(i) Caption and identification of parties and case

Name of appellant/defendant, court of first instance, case number, date of judgment.
Clearly state: “This petition for leave to appeal (or cassation) is filed concurrently with the notice of appeal (or cassation).”

(ii) Statement of facts and procedural background

A concise but complete summary of the case: indictment/charge, trial, judgment, sentence, reading of judgment date, appeal (if any) and outcome.
Emphasise the factual and legal context that gives rise to the petition.

(iii) Grounds for leave

This is the core segment. The petition should argue why leave should be granted, by setting out reasons such as:

The case raises a significant question of law (e.g., first-instance interpretation, conflict with precedent, or unsettled legal issue).
The factual circumstances are complex or novel, making the ordinary review insufficient and entitling further scrutiny.
There is evidence of error in procedure, violation of rights, or manifest injustice (for example, denial of defence rights, material mis-application of law).
The appellant/defendant was subject to a sentence or decision that merits review in the interest of justice.

Use phrasing such as: “This case presents an issue of public importance which ought to be examined by the highest court,” or “The facts present more than one possible legal view, thus justifying access to cassation.”

(iv) Request

A specific request that the judge grant permission for the appeal/cassation.
If applicable, request that the judge make the appropriate endorsement or sign the order.
Provide the name/position of the judge from whom leave is sought.

(v) Signature, date and formalities

Ensure the petition is signed by counsel (or the party if unrepresented).
Indicate the date of submission and attach supporting documents (judgment copy, appeal/cassation notice, any dissenting opinion if relevant).
Verify that filing fees (if required) are paid as applicable.

5.3 Drafting style – best practices

Use clear, formal legal language; avoid overly technical phrasing that may obscure the reasoning.
Break the petition into headings/sub-headings (Facts, Grounds, Request) for readability.
Avoid verbosity: be concise but comprehensive — judges appreciate clarity of argument.
Emphasise the policy or justice-based rationale (especially in leave petitions) rather than mere repetition of facts.
Map every argument to a legal proposition or precedent (if available) — show that the case is not routine.

6. What happens after filing the petition?

6.1 Initial review and decision on leave

Once filed, the court will send the petition to the judge authorised to decide on leave.
The judge reviews whether the case merits further review (appeal or cassation) based on the grounds advanced.
The judge may grant or deny leave.

6.2 If leave is granted

The petition becomes effective; the appeal or cassation proceeds, and the case is forwarded to the higher court.
The appellant/defendant must then comply with any additional procedural requirements of the appellate or cassation court (e.g., submission of record, brief, payment of fees).

6.3 If leave is denied

The decision on the petition will be part of the case file; the appellant/defendant may have limited or no further recourse (depending on statutory scheme).
If the statute treats the decision as final, the judgment of the lower court stands.
In some cases only part of the appeal/cassation may be accepted (for example, where leave is granted with respect to certain legal issues but not others) — the court may then proceed on the permitted issues.

6.4 Strategic considerations

Time runs: anticipate the petition deadline and the appeal/cassation deadline concurrently.
Prepare the full appeal/cassation notice in tandem with the petition (since many laws require them together).
If leave is denied, reassess whether any other remedy remains (e.g., complaint for judicial review, constitutional relief, mercy petition) — inform the client accordingly.

7. Key pitfalls and how to avoid them

7.1 Missing the time-limit

A failure to file within the prescribed time (commonly 30 days) generally forfeits the right. Ensure tracking of the ‘date of reading’ of judgment. ThaiLawOnline+1

7.2 Separating the petition from the appeal/cassation

In many cases the law requires simultaneous filing of the petition and the appeal/cassation notice. If not done, the court may reject the appeal on procedural grounds.

7.3 Failing to identify the correct judge or basis for leave

Incorrectly naming the judge, or failing to demonstrate that the judge is in the authorised category, may invalidate the petition. Also failure to articulate why the case merits leave (i.e., treat it as a routine appeal) will likely result in denial.

7.4 Poor drafting of grounds

A petition that simply repeats the appeal grounds without showing significance, novelty or the need for higher-court review will often be rejected. Counsel must highlight the threshold test (legal significance, precedent conflicts, public interest) not just disagreements with fact-finding.

7.5 Overlooking fees or formalities

Some courts require payment of filing fees or adherence to particular formatting/filing rules (court clerks, electronic vs paper). Failing to comply may delay or invalidate the petition.

8. Practical checklist for counsel

Before filing a petition for leave to appeal or cassation, counsel should confirm:

9. Illustrative scenario

To illustrate, imagine a defendant is convicted by a trial court and sentenced to 2 years’ imprisonment. The defence files a notice of cassation, but because the sentence is below a threshold (for example, 3 years) the law treats the decision as final unless the trial judge grants permission. Counsel prepares a petition for leave to cassation, outlining that the case raises an unsettled question of statutory interpretation of the applicable offence, and that a dissenting opinion was issued by one of the judges in the appeal. The petition names the judge who dissented, attaches the appeal record and the cassation notice, pays the required fee, and files all documents within the 30-day window. The judge reviews and grants permission, and the case is forwarded to the Supreme (Cassation) Court for full review.

By contrast, had counsel omitted the petition, or filed it after the 30-day period, or failed to root the argument in significance/novelty grounds, the cassation request might have been denied outright — thus closing the door on meaningful review.

10. The role of defence counsel and client communication

Given the high-stakes nature of criminal cases (particularly when liberty is at risk), the defence counsel must:

Advise the client at the earliest stage whether their case falls into the category requiring a petition for leave.
Explain the implications: that failure to apply for leave might forfeit appellate/cassation rights.
Coordinate the preparation of both the petition and appeal/cassation notice simultaneously.
Set realistic expectations: obtaining leave does not guarantee success in the higher court; it simply opens the gate for review.
Maintain clear time-management and document-management protocols to avoid missing deadlines.

Effective client communication ensures that the client understands that this procedure is not a mere formality but a strategic and determinative step in their appellate journey.

11. Summary and conclusion

In summary, the petition for leave to appeal or cassation in criminal proceedings is a pivotal step when Thai law limits automatic access to higher review levels. Defence counsel must treat this step with equal seriousness as the content of the appeal/cassation itself. The key take-aways are:

Analyse whether the case is one requiring leave (thresholds, categories).
Prepare the petition and appeal/cassation notice together, within the time-limit, with correct judge identified.
Draft the petition to show why the case merits higher-court review (legal significance, novelty, complexity, rights protection).
After filing, monitor the outcome and be ready for the higher-court procedure if leave is granted — or advise the client on alternative remedies if leave is denied.

By diligent preparation and strategic counsel (particularly when engaged via a lead law firm in Bangkok), the risk of losing appellate rights due to procedural mis-steps can be minimised. In criminal law — where liberty is at stake — these procedural avenues are not technicalities but essential gateways.