Ask a lawyer:
whether evidence obtained contrary to constitutional guarantees that it should be excluded

mwakili.com

Sources I will rely on

Constitution of Kenya, 2010

Article 2 – Supremacy of the Constitution
Article 20, 22, 23 – Enforcement of the Bill of Rights
Article 24 – Limitations of rights
Article 25(c) – Right to a fair trial (non‑derogable)
Article 31 – Right to privacy
Article 50 (Fair hearing) – especially Article 50(4) (core provision on exclusion of unconstitutionally obtained evidence) (nairobilawmonthly.com ↗)

Statutes

Evidence Act, Cap 80 – especially:
- Section 25A (confessions)
- Sections on admissibility and relevance generally
Criminal Procedure Code, Cap 75 – especially:
- Sections 118–121 (search warrants and seizure) (new.kenyalaw.org ↗)
National Police Service Act – provisions on arrest, search, and use of force (as background to when searches/arrests may become unconstitutional).

Key Kenyan cases on illegally / unconstitutionally obtained evidence

David Ogolla Okoth v Chief Magistrate Court, Kibera & 2 others [2016] eKLR – first major High Court interpretation of Article 50(4). (new.kenyalaw.org ↗)
Njonjo Mue & another v Chairperson of IEBC & 3 others (Presidential Election Petition 4 of 2017) [2017] KESC 45 (KLR) – Supreme Court ruling on leaked IEBC internal memos. (new.kenyalaw.org ↗)
United Airlines Ltd v Kenya Commercial Bank Ltd [2017] eKLR (Court of Appeal) – noted that the 2010 Constitution changed the old common‑law rule based on Kuruma. (new.kenyalaw.org ↗)
Okiya Omtatah Okoiti & 2 others v Attorney General & 11 others [2020] KECA 589 (KLR) – Court of Appeal clarifying that Article 50(4) can apply in civil/constitutional proceedings, not just criminal trials. (new.kenyalaw.org ↗)
Philomena Mbete Mwilu v DPP & 3 others [2019] eKLR – High Court on bank records obtained by misusing a court order; applied a detailed test on when to exclude evidence. (new.kenyalaw.org ↗)
Republic v Ali & 2 others (Criminal Revision E055 of 2023) [2024] KEHC 10969 (KLR) – digital evidence from mobile phones seized without proper warrant. (new.kenyalaw.org ↗)
Yaqoob & 6 others v Republic (Criminal Appeal E022 of 2023) [2025] KEHC 7119 (KLR) – recent High Court appellate decision reviewing Kenyan and foreign law on illegally obtained evidence. (new.kenyalaw.org ↗)

All these decisions are available on the Kenya Law website (and some also on SheriaHub).

1. The basic constitutional rule: Article 50(4)

Article 50(4) of the Constitution is the central provision here. In substance, it says:

Evidence obtained in a way that violates a right or fundamental freedom in the Bill of Rights must be excluded if admitting it would:

render the trial unfair, or

otherwise be detrimental to the administration of justice. (nairobilawmonthly.com ↗)

So, Kenyan law does recognise an exclusionary rule for evidence obtained contrary to constitutional guarantees. But there are two critical points:

There must first be a real violation of a right in the Bill of Rights when the evidence was obtained (e.g. violation of privacy, freedom from torture, right to property, right to fair trial, etc.).
Exclusion is not automatic just because the evidence was illegally or unconstitutionally obtained: the court must ask whether admitting that evidence would either:
- make the trial unfair, or
- seriously undermine the broader administration of justice (public confidence, deterrence of abuse, etc.).

This “two‑stage test” runs through almost all modern Kenyan case law on this subject. (new.kenyalaw.org ↗)

2. How did things work before 2010, and what changed?

Before the 2010 Constitution, Kenya followed common‑law principles as explained in Kuruma son of Kaniu v R [1955] AC 197, a Privy Council decision. In essence, Kuruma said:

The test of admissibility was simply relevance.
If the evidence was relevant, the court did not care how it had been obtained, even if it was stolen or obtained illegally.

Kenyan courts applied that approach for many years. (new.kenyalaw.org ↗)

After 2010:

The Constitution introduced Article 50(4), borrowing heavily from section 35(5) of the South African Constitution, which deliberately limits the Kuruma rule. (the-star.co.ke ↗)
The Court of Appeal has stated clearly that the 2010 Constitution “changed that position” and that Kuruma is no longer good law in Kenya when it comes to evidence obtained in violation of constitutional rights. (new.kenyalaw.org ↗)

So today, the starting point is:

Relevant evidence is not automatically admissible if obtained in breach of constitutional rights. The court must apply Article 50(4).

3. The two‑stage test Kenyan courts apply

Stage 1 – Was there a violation of a constitutional right in obtaining the evidence?

The party challenging the evidence (often the accused or a petitioner) must show, with evidence, that:

a particular right in the Bill of Rights (privacy, property, dignity, freedom from torture, fair trial, etc.)
was unjustifiably violated in the way the evidence was obtained. (new.kenyalaw.org ↗)

Examples:

Illegal search & seizure: police seize property (a car, phone, documents) without any warrant or lawful basis where a warrant was required – violating:
- Article 31 (privacy),
- Article 40 (property), and
- aspects of Article 29 (security of the person). (new.kenyalaw.org ↗)
Misuse of a court order: investigators use a warrant or bank‑inspection order that was granted in respect of one account to “fish” through other unrelated accounts, as in Mwilu v DPP – violating privacy under Article 31 and fair trial guarantees. (new.kenyalaw.org ↗)
Coerced confession or torture: interrogations conducted through threats, beatings or torture violate Articles 25(a) and 29. Any confession or derivative evidence is seriously tainted.

If there is no real constitutional violation (for example, only a minor technical defect in paperwork but the search itself was lawful and proportionate), Article 50(4) may not be triggered.

Stage 2 – Would admitting the evidence make the trial unfair or harm the administration of justice?

If a rights violation is established, the court then decides whether to exclude the evidence. It asks:

Will admission make the specific trial unfair? (focus on the individual accused or parties)
Even if the trial might technically remain “fair”, would admitting the evidence nevertheless be “detrimental to the administration of justice”? (public interest, integrity of the system, deterrence of abuse) (new.kenyalaw.org ↗)

Kenyan courts have adopted wording from South African cases like S v Tandwa and Gumede v S, as quoted approvingly in Mwilu and later cases:

Evidence should be excluded where its admission either:
- renders the trial unfair, or
- is otherwise detrimental to the administration of justice (e.g. encourages police/state misconduct, undermines public confidence in courts). (new.kenyalaw.org ↗)

Important: This means there is no rule of automatic exclusion. The judge must balance competing factors:

seriousness and deliberate nature of the rights violation,
centrality of the evidence to the case,
availability of other lawful evidence,
the gravity of the offence or issue,
and the long‑term impact on justice if such conduct is condoned.

4. What have Kenyan courts actually done in leading cases?

(a) David Ogolla Okoth v Chief Magistrate Court, Kibera (2016)

Police seized a motor vehicle without proper warrants; the petitioner argued this violated his rights and that all resulting evidence should be excluded.
The High Court held:
- Yes, there is an inherent exclusionary rule in Article 50(4).
- But exclusion is not automatic; the petitioner’s view that any improperly obtained evidence must terminate a trial was rejected.
- The court emphasised:
  1. You must prove a right in the Bill of Rights was unjustifiably violated, and
  2. Show that admitting the evidence would render the trial unfair or be detrimental to the administration of justice. (new.kenyalaw.org ↗)

This case is often cited as the clearest early exposition of the Article 50(4) test.

(b) Njonjo Mue & another v Chairperson of IEBC & 3 others (2017, Supreme Court)

In the Presidential Election Petition, the petitioners relied on internal IEBC memos, whose lawful acquisition was questionable.
The Supreme Court:
- Traced the history from common law to Article 50(4).
- Reaffirmed that evidence must be obtained in accordance with the Constitution and the law.
- Applied the two‑step test: show unjustified violation + unfairness/detriment.
- Treated Article 50(4) as applicable even in the special context of election petitions. (new.kenyalaw.org ↗)

The Court signalled that parties (including petitioners against the State) cannot rely on “stolen” or unlawfully accessed documents if admitting them would impair fairness or the integrity of justice.

(c) United Airlines v KCB (2017, Court of Appeal) and Okiya Omtatah case (2020)

In United Airlines, the Court of Appeal:
- Noted that illegally obtained evidence is no longer simply admissible whenever relevant; the Constitution changed that.
- However, there was an obiter suggestion that Article 50(4) might be confined to criminal trials because it speaks of “trial” and rights of “accused persons”. (new.kenyalaw.org ↗)
In Okiya Omtatah Okoiti & 2 others v AG & 11 others (2020), the same Court clarified:
- Article 50 deals generally with “fair hearing” and protects “every person” in Article 50(1), not only accused persons.
- Therefore, Article 50(4) may justify exclusion of unlawfully obtained evidence in civil and constitutional matters as well, wherever admitting it would harm the administration of justice. (new.kenyalaw.org ↗)

This is very important: the exclusionary principle is not limited to criminal cases.

(d) Philomena Mbete Mwilu v DPP & 3 others (2019)

Concerned bank records and financial information relating to the then Deputy Chief Justice.
Investigators used a court order obtained for one bank account to access other accounts in a different bank, which the court held was a serious, deliberate violation of her right to privacy under Article 31.
The High Court:
- Adopted the South African approach: evidence is excluded when its admission would render the trial unfair or be otherwise detrimental to the administration of justice.
- Held that the DCI’s conduct was “egregious and objectively unreasonable”, and that to allow reliance on such evidence would be detrimental to the administration of justice. The impugned evidence was therefore excluded. (new.kenyalaw.org ↗)

This is a textbook example of the court using public policy and systemic integrity (not just fairness to the individual) to justify exclusion.

(e) Digital evidence & phones – Republic v Ali & 2 others (2024)

Police obtained electronic evidence from the accused persons’ mobile phones without a proper warrant.
The High Court, citing Mwilu and South African authority, reiterated:
- Article 50(4) does not mandate automatic exclusion.
- The key question is whether admission would violate fair trial rights or harm the administration of justice.
The court examined:
- The seriousness and context of the violation,
- The nature of the offences,
- The importance of the evidence. (new.kenyalaw.org ↗)

This shows the same balancing test being applied to modern electronic evidence.

(f) Yaqoob & 6 others v Republic (2025)

Appellate decision summarising Kenyan and comparative jurisprudence on illegally obtained evidence.
It confirms:
- The 2010 Constitution overturned the old common‑law rule (Kuruma).
- Article 50(4) is now the governing standard.
- Illegally obtained documents may be excluded where obtained in breach of constitutional norms (e.g. accessing internal memos without lawful authority). (new.kenyalaw.org ↗)

5. So, must evidence obtained contrary to constitutional guarantees always be excluded?

In Kenyan law today, the position can be summarised as follows:

If there is no violation of a constitutional right, Article 50(4) is not engaged; the evidence will generally be admissible if it meets ordinary rules of relevance and admissibility under the Evidence Act.
If there is a violation of a right in the Bill of Rights, then:
- Article 50(4) says such evidence shall be excluded if admitting it would:
  - make the trial unfair, or
  - otherwise be detrimental to the administration of justice.
There is no automatic/blanket exclusion rule. The courts consistently reject the argument that:
- “any” illegally obtained evidence must be excluded.
  This was clearly explained in David Ogolla and adopted by the Supreme Court in Njonjo Mue and subsequent cases. (new.kenyalaw.org ↗)
In practice, the more serious and deliberate the constitutional breach, and the more it involves core non‑derogable rights (e.g. freedom from torture, the right to a fair trial under Article 25(c)), the more likely the evidence will be excluded.
Conversely, where:
- the violation is technical or minor,
- the evidence is highly reliable and crucial to resolving a very serious matter, and
- exclusion would gravely harm society’s interest in having the case decided on its merits,
  a court might still admit the evidence – but it must justify why admission does not unfairly prejudice the accused and does not seriously damage the justice system.

6. Some practical illustrations

Example 1 – Evidence obtained through torture

Police torture a suspect to force a confession, then recover a weapon based on that coerced information.
This violates:
- Article 25(a) & Article 29 (freedom from torture and cruel, inhuman or degrading treatment), and
- Article 50(2)(l) (right not to be compelled to make a confession).
Because these rights are non‑derogable and the breach is extreme, the court is very likely to find that:
- admitting the confession would clearly render the trial unfair, and
- admitting derivative evidence may also be detrimental to the administration of justice, as it would encourage torture.
Result: strong case for exclusion of both the confession and possibly the derivative evidence.

Example 2 – Warrantless search of a house

Police enter a home without a warrant in circumstances where a warrant could and should have been obtained, and seize drugs or firearms.
Rights affected:
- Article 31 (privacy),
- Article 40 (property), possibly Article 29 (security of person).
The court must balance:
- The seriousness of the offence (e.g. drugs trafficking, terrorism vs. a minor offence),
- Whether the officers acted in good faith or in blatant disregard of the law,
- Whether there were urgent circumstances justifying the lack of a warrant,
- Whether there is other independent evidence.
Depending on the balancing, the court may:
- exclude the evidence (especially where the conduct was deliberate and abusive, as in Mwilu), or
- admit it but possibly censure the conduct in its judgment.

Example 3 – Staff email leaked by a disgruntled employee in a civil suit

An employee downloads confidential internal emails, contrary to company policy and possibly contrary to data‑protection or privacy rights, and then uses them in an employment or commercial dispute.
There may be an argument that the manner of acquisition violated the privacy rights of other parties.
Following Okiya Omtatah and labour court decisions like Muchiri v Pernod Ricard, courts have:
- recognised that Article 50(4) can apply in civil/employment disputes, but
- will still undertake the fairness/administration of justice balancing exercise. (sheriahub.com ↗)

The court will look at whether the documents reveal serious wrongdoing, whether there were lawful ways to obtain them (e.g. discovery), and whether admission would incentivise or condone serious privacy breaches.

7. Short answer to your question

So, addressing your question directly:

Whether evidence obtained contrary to constitutional guarantees should be excluded?

Under the Constitution of Kenya, 2010, yes, such evidence is liable to exclusion, but not automatically. The position is:

Step 1: You must show the evidence was obtained in a way that violated a right or fundamental freedom in the Bill of Rights.
Step 2: If so, the court must exclude the evidence if admitting it would:
- render the trial unfair, or
- be detrimental to the administration of justice (for example by encouraging official misconduct or undermining public confidence in the courts).

This is the constitutional exclusionary rule in Article 50(4), as interpreted in cases like David Ogolla Okoth, Njonjo Mue, Mwilu, Okiya Omtatah, Republic v Ali, and Yaqoob. (new.kenyalaw.org ↗)

If you let me know whether you’re dealing with a criminal case, a civil/constitutional matter, or preparing for an exam, I can:

Help you structure a model exam answer on this issue, or
Apply this doctrine to your specific facts and suggest concrete arguments for excluding or admitting the contested evidence.