The Principle of Good Faith is one of the most fundamental doctrines of Thai civil law. Enshrined in Section 5 of the Thai Civil and Commercial Code, it governs the exercise of legal rights and the performance of obligations in virtually every type of civil dispute, including contract, property, tort, and commercial litigation.

Even where a party appears to have a valid legal right or contractual entitlement, Thai courts may refuse to enforce that right if it has been exercised in bad faith.

This article explains the Good Faith Principle under Thai law, its legal significance, common examples of bad faith, the burden of proof, and how lawyers can use this principle strategically in civil litigation.

What Is the Principle of Good Faith?

Section 5 of the Thai Civil and Commercial Code provides:

“Every person must, in the exercise of his rights and in the performance of his obligations, act in good faith.”

This provision establishes a general legal principle that applies throughout Thai private law. It requires every individual to exercise legal rights honestly, fairly, and consistently with accepted standards of conduct.

The principle reflects the well-known equitable doctrine commonly referred to as the Clean Hands Doctrine:

A party seeking the protection of the court must come with clean hands.

Accordingly, courts may refuse to protect a legal right if it has been exercised dishonestly, unfairly, or for an improper purpose.

Why Is the Good Faith Principle Important?

The Good Faith Principle is often described as the backbone of Thai civil law because it enables courts to achieve fairness beyond the literal wording of statutes or contracts.

Although a party may technically possess a legal right, that right may not receive judicial protection if the court concludes that it has been exercised in bad faith.

For this reason, proving—or disproving—good faith can often become the decisive issue in a civil lawsuit.

Common Forms of Bad Faith under Thai Law

Thai courts have identified several situations in which the exercise of legal rights may constitute bad faith.

1. Acting Inconsistently with One’s Previous Conduct

A party who has consistently accepted or tolerated a particular situation may later be prevented from asserting legal rights in a manner that unfairly contradicts previous conduct and causes prejudice to another party.

Examples include:

Allowing another person to manage property or business affairs for many years before suddenly attempting to invalidate those actions.
Remaining silent while another party relies upon one’s conduct and later asserting legal rights that are inconsistent with that previous conduct.
2. Relying on Rights Created by One’s Own Gross Negligence

A person may be found to have acted in bad faith when attempting to rely upon legal rights arising from their own serious negligence.

Examples include:

Signing blank documents and allowing another person to complete them later.
Failing to safeguard important legal documents, such as land title deeds, resulting in forgery or fraudulent transactions.
3. Using Legal Rights to Circumvent the Law

Even where a transaction appears legally valid on its face, the court may conclude that it was conducted in bad faith if its true purpose was to evade legal requirements.

Examples include:

Understating the purchase price or rental value of property to reduce taxes.
Using another person’s name to hold property in order to avoid statutory ownership restrictions.
4. Exploiting Legal Rights Unfairly

A party who uses superior bargaining power or legal technicalities to gain an unfair advantage may also be considered to have acted in bad faith.

Examples include:

Requiring a debtor to sign loan documents for an amount exceeding the actual debt.
Intentionally delaying debt collection in order to accumulate excessive interest before filing a lawsuit.
Who Has the Burden of Proving Bad Faith?

Section 6 of the Thai Civil and Commercial Code provides an important evidentiary rule:

Every person is presumed to act in good faith unless proven otherwise.

Consequently, the burden of proof rests upon the party alleging bad faith.

Mere allegations are insufficient. The accusing party must present credible documentary evidence, witness testimony, or surrounding circumstances capable of persuading the court that the opposing party acted dishonestly or unfairly.

Can the Court Raise the Issue of Good Faith on Its Own?

Yes.

The Principle of Good Faith is regarded as a matter of public policy under Thai law.

Accordingly, Thai courts may consider the issue even if neither party expressly raises it during the proceedings.

Nevertheless, as a matter of litigation strategy, lawyers should clearly plead bad faith whenever the facts support such an argument. Doing so allows the issue to be fully examined through documentary evidence and witness testimony.

Litigation Strategies for Lawyers

The Principle of Good Faith should be considered in virtually every civil dispute.

For Defendants

A defendant should carefully examine whether the claimant has exercised legal rights in bad faith by considering questions such as:

Has the claimant acted inconsistently with previous conduct?
Is the claim based upon the claimant’s own gross negligence?
Is the legal right being used to circumvent the law?
Is the claimant attempting to obtain an unfair advantage?

Any allegation of bad faith should be supported by detailed factual pleadings and persuasive evidence.

For Claimants

Claimants should proactively demonstrate that they have exercised their rights honestly and fairly.

Supporting evidence should explain:

Why legal rights were exercised.
Whether previous conduct was consistent.
Why the claimant acted reasonably throughout the transaction or dispute.

Presenting evidence of good faith from the outset can reduce the likelihood of successful bad faith allegations.

Frequently Asked Questions
What is the Principle of Good Faith under Thai law?

The Principle of Good Faith requires every person to exercise legal rights and perform legal obligations honestly, fairly, and in accordance with accepted standards of conduct.

Can a Thai court refuse to enforce a legal right exercised in bad faith?

Yes. Even where a legal right technically exists, a Thai court may decline to recognize or enforce that right if it concludes that it has been exercised in bad faith.

Who must prove bad faith?

Because Thai law presumes that everyone acts in good faith, the burden of proving bad faith rests on the party making the allegation.

Conclusion

The Principle of Good Faith under Section 5 of the Thai Civil and Commercial Code is one of the most important doctrines in Thai private law. It serves as a safeguard against unfair or abusive exercises of legal rights and enables courts to reach outcomes that are both legally correct and equitable.

Whether you are pursuing a claim or defending one, understanding how Thai courts apply the Good Faith Principle can significantly influence litigation strategy and, in many cases, determine the outcome of the dispute.

If you are involved in a civil dispute in Thailand, obtaining legal advice at an early stage can help assess whether issues of good faith may affect your rights and strengthen your position before court proceedings begin.