The concept of “fruits of the poisonous tree,” borrowed from the Anglo-American legal tradition, has become an important tool in criminal proceedings in Ukraine to ensure the legality of evidence and protect the rights of participants in the process. It stipulates that evidence obtained through illegal actions, as well as derivative evidence, is inadmissible and cannot be used to prove a person’s guilt.
The principle of “fruits of the poisonous tree” in the criminal process of Ukraine is enshrined in the Criminal Procedure Code of Ukraine (CPC), including:
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Article 86 of the CPC, which provides that evidence is admissible only if obtained in accordance with the law;
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Article 87 of the CPC, which defines as inadmissible evidence obtained as a result of significant violations of human rights and freedoms, as well as derivative evidence obtained through such violations;
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Article 92 of the CPC, according to which the burden of proving the admissibility of evidence lies with the party submitting it;
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Article 94 of the CPC, which provides that the court independently assesses the admissibility of evidence, without attributing any predetermined strength to any evidence.
These norms are consistent with Article 62 of the Constitution of Ukraine, which prohibits basing charges on illegally obtained evidence, and Article 6 of the European Convention on Human Rights (ECHR), which guarantees the right to a fair trial. The Supreme Court in its decisions repeatedly refers to precedents of the European Court of Human Rights, including the case Brandstetter v. Austria (1991, § 67), emphasizing the need for an adversarial process and the possibility of challenging evidence.
The principle of “fruits of the poisonous tree” provides that the initial violation (e.g., illegal investigative action) makes not only the direct results of that violation inadmissible but also all derivative evidence if their acquisition became possible due to illegal information.
In order to reduce the number of human rights violations during the pre-trial investigation stage, which can also lead to the inadmissibility of obtained evidence according to the doctrine of “fruits of the poisonous tree,” the CPC provides for judicial control over the observance of rights, freedoms, and interests of individuals in criminal proceedings, exercised by investigating judges.
Thus, the CPC stipulates that decisions on the most significant restrictions of a person’s rights (e.g., permission for searches, covert investigative (search) actions, detention of a person, etc.) are made not by the investigator or prosecutor, but by an independent arbiter – the investigating judge.
However, when making relevant decisions, the investigating judge is not immune from errors.
This article analyzes the current judicial practice of the Supreme Court regarding the procedural consequences of obtaining evidence based on illegal decisions of investigating judges, issued on the basis of inadmissible evidence.
In case No. 754/12820/15-k, considered by the Supreme Court on February 5, 2019 (proceedings No. 51-3099km18), the accused was charged with crimes related to the illegal circulation of psychotropic substances, precursors, medicines, and weapons. The prosecution based the charges on evidence obtained as a result of operational purchases and searches authorized by the decisions of investigating judges. The first-instance court acquitted the accused, excluding the evidence as inadmissible due to procedural violations. The appellate court upheld this verdict unchanged, and the Supreme Court partially upheld the cassation appeal, overturning the decision on acquittal under Article 263 of the Criminal Code but leaving the rest of the decision intact. The central violation was the failure of the prosecution to submit prosecutor’s resolutions sanctioning operational purchases, as required by Article 246 of the CPC. This violation led to the inadmissibility of the primary evidence since it was obtained without proper procedural formalities. The decisions of the investigating judge authorizing searches were based solely on this inadmissible data, resulting in the exclusion of derivative evidence, such as search results and expert opinions, in accordance with the requirements of Article 87 of the CPC. The Supreme Court emphasized that the formal existence of the investigating judge’s decision does not eliminate the primary violation if it is based on illegal sources, which is a direct application of the “fruits of the poisonous tree” principle. The court also stressed that the court hearing the case on the merits has the authority to review the validity of the investigating judges’ decisions, even if they were not separately challenged, ensuring the implementation of the adversarial principle provided for in Article 22 of the CPC.
The decision of the Supreme Court dated February 21, 2023, in case No. 683/1507/16-k (proceedings No. 51-8872km18) expands the understanding of the application of the “fruits of the poisonous tree” principle in cases related to special investigative techniques and searches. The accused in this case were acquitted due to lack of evidence of guilt, particularly due to the recognition of inadmissible evidence obtained in the course of an operational search case and searches. The prosecution appealed the decision, arguing that the appellate court incorrectly assessed the admissibility of evidence and ignored the legality of the investigating judges’ resolutions authorizing searches. The Supreme Court dismissed the cassation appeal but acknowledged that the appellate court mistakenly evaluated the legality of the investigating judges’ resolutions instead of limiting itself to assessing the admissibility of the evidence obtained based on them (legitimized by the resolutions). The lower courts found the protocols of special investigative techniques conducted before entering information into the Unified Register of Pre-trial Investigations inadmissible, based on the closure of the operational search case on rehabilitative grounds and the destruction of its materials, which prevented the verification of the legality of the measures. Violations of Article 214 of the CPC, which prohibits investigative actions before entering information into the register, except for the scene examination, also confirmed the inadmissibility of the evidence. The Supreme Court supported these findings; however, the Court criticized the appellate court for assessing the legality of the investigating judges’ resolutions on authorizing searches, as the courts do not have the authority to review the legality of such decisions but can only assess the admissibility of the evidence obtained. In this case, the impossibility of assessing the legality of the investigating judges’ resolutions was further substantiated by the absence of defense objections submitted at the preparatory court session regarding these resolutions, as provided for in Part 3 of Article 309 of the CPC.
Indeed, the decision of the Supreme Court dated April 15, 2025, in case No. 127/15521/24 (proceedings No. 51-231km25) confirms the need to consider objections of the parties regarding the investigating judges’ resolutions at the preparatory court session. The Court overturned the decisions of the lower instances that ignored the prosecutor’s objections to the investigating judge’s resolution canceling the decision to suspend the investigation. The Supreme Court established that the court is obliged to examine objections submitted in accordance with Part 3 of Article 309 of the CPC, otherwise, it constitutes a significant violation of the adversarial principle (Article 22 of the CPC) and the requirements for reasoning decisions (Articles 370, 419 of the CPC). The investigating judges’ resolutions do not have prejudicial significance, and the court has full discretion to reassess them.
In case No. 489/6721/21, considered by the Supreme Court on June 6, 2023 (proceedings No. 51-4081km22), the appellate court lawfully refused to initiate proceedings on the prosecutor’s complaint against the investigating judge’s resolution canceling the decision to suspend the investigation, as such resolutions are not subject to separate appellate review. However, in the mentioned decision, the Supreme Court once again emphasizes that parties are obliged to submit objections at the preparatory court session if they wish to exercise the right to judicial control over the investigating judges’ resolutions made during the pre-trial investigation stage and not subject to separate appellate review.
Algorithm for Evaluating and Challenging the Admissibility of Evidence
Based on the practice of the Supreme Court, an algorithm for evaluating and further challenging the admissibility of evidence obtained based on investigating judges’ resolutions relying on inadmissible evidence is proposed:
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Identification of the Evidence Source: Determine if the evidence comes from an investigative action sanctioned by the investigating judge’s resolution (e.g., search, special investigative technique).
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Verification of the Legality of Primary Actions: Ensure that primary investigative actions were carried out in accordance with the CPC, particularly in the presence of procedural decisions sanctioning such actions.
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Analysis of the Justification of the Investigating Judge’s Resolution: Examine whether the resolution is based on admissible primary evidence and whether the investigating judge had other independent sufficient sources of evidence (information) for issuing the resolution.
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Assessment of the Significance of Violations: Determine whether the violation is “significant” under Article 87 of the CPC, e.g., violation of the right to privacy or failure to comply with the procedures for conducting special investigative techniques.
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Establishment of the Causal Relationship: Verify whether the evidence is derivative of the inadmissible primary evidence, applying the “fruits of the poisonous tree” principle.
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Submission of Objections at the Preparatory Court Session: It is mandatory to submit objections at the preparatory court session, as provided for in Part 3 of Article 309 of the CPC; otherwise, the right to appeal is forfeited;
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Filing a Motion to Exclude Evidence: File a motion to declare the evidence inadmissible if the violations are confirmed (Article 89 of the CPC).
The practice of the Supreme Court obliges courts to carefully analyze the legality of primary evidence and the investigating judges’ resolutions during the judicial proceedings. This provides defense lawyers with an effective tool to challenge evidence obtained based on illegal resolutions. For its full utilization, defense lawyers must timely submit objections regarding the legality of the investigating judges’ resolutions and the admissibility of such evidence at the preparatory court session, as the failure to raise objections at this stage may lead to the loss of the right to appeal.