Wallet attribution and proposed Rule 104(b): judge vs jury roles

Wallet attribution is rarely a single fact. It is a chain: the address received funds, the address belongs to the defendant, and the defendant controlled the private key on the operative date. The blockchain proves only the first link. The rest rests on off-chain evidence: exchange records, device artifacts, signed messages, or admissions. At every link, the same question arises: is this a preliminary fact the judge decides, or a conditional fact the jury resolves?

Federal Rule of Evidence 104 governs that line. On August 14, 2026, the Judicial Conference Committee on Rules of Practice and Procedure published proposed amendments to Rule 104 for public comment. The proposal is not law, binds no courtroom, and is projected to take effect December 1, 2028 if adopted and transmitted to Congress, absent congressional action. This article explains the judge-jury allocation under the December 1, 2024 rules in force today, what the proposal alters, and how to build an evidentiary foundation that works under either standard.

Wallet Attribution Is a Chain of Conditional Facts

A transaction record confirms that address X transferred value to address Y at a specific block height and timestamp, but does not identify who controlled either address. Attribution maps an address to an individual through external evidence: exchange withdrawal records, seed phrases on seized devices, cryptographic signatures, or party admissions.

Each supporting fact is conditional. The relevance of an exchange record depends on whether account data connects the address to the defendant. The relevance of a recovery phrase depends on whether it reconstructs the target key. When relevance depends on whether another fact exists, Rule 104(b) governs and the court applies a screening standard rather than a finding standard.

Related articles address neighboring questions: Understanding Wallet Ownership Evidence catalogs evidence types, while Blockchain Evidence in Litigation and What Makes Blockchain Evidence Admissible Under Federal and Missouri Rules examine authentication and expert standards. This article focuses on the division between judge-decided admissibility prerequisites and jury-decided conditional inferences.

Current Rule 104: The Baseline You Argue Today

Rule 104(a): Judge-decided preliminary questions

Under the Federal Rules of Evidence effective December 1, 2024, Rule 104(a) requires the court to decide preliminary questions of qualification, privilege, or admissibility, unbound by evidence rules except privilege. Bourjaily v. United States, 483 U.S. 171, 175 (1987), established that preliminary facts must be proved by a preponderance of the evidence. In attribution disputes, judge-decided matters include expert qualification, Rule 702 reliability, hearsay, privilege, and Rule 902 certification compliance.

Rule 104(b): Conditional facts that go to the jury

Current Rule 104(b) provides: "When the relevance of evidence depends on whether a fact exists, proof must be introduced sufficient to support a finding that the fact does exist. The court may admit the proposed evidence on the condition that the proof be introduced later." Under Huddleston v. United States, 485 U.S. 681, 687-690 (1988), the court does not weigh credibility or find facts; it decides only whether the jury could reasonably find the conditional fact by a preponderance of the evidence. Rule 104(e) preserves the jury's role regarding weight, while Rule 104(d) protects an accused testifying on preliminary matters from broader cross-examination.

Where Rule 702 gatekeeping fits

Do not confuse Rule 104(b) with Rule 702 gatekeeping. Under Rule 104(a), the judge determines whether an expert's opinion rests on reliable methodology, codified as a preponderance standard in Rule 702 in 2023. Under Rule 104(b), contested predicate facts belong to the jury. An expert may explain transaction flows and clustering heuristics; whether the defendant controlled the wallet is for the jury unless no reasonable jury could so find.

What the August 2026 Proposal Would Change

Status: proposed, not law

The publication notice and Preliminary Draft of Proposed Amendments, dated August 2026, set the timeline. Following late-2025 discussions, the Advisory Committee voted unanimously on May 7, 2026 to recommend publication, transmitting its May 17, 2026 report to the Standing Committee. The preliminary draft appeared on August 14, 2026, with comments due February 15, 2027. The package covers Rule 104 and Rule 902(1) (tribal public records), carrying a projected effective date of December 1, 2028 under the Rules Enabling Act.

Proposed 104(a): preponderance in the text

The proposal adds an explicit sentence to Rule 104(a): "Unless these rules provide otherwise, the proponent must establish the existence of a preliminary fact by a preponderance of the evidence." That sentence codifies Bourjaily in the rule text, paralleling the 2023 amendment to Rule 702.

Proposed 104(b): conditional relevance goes away

The proposal deletes the "proof sufficient to support a finding" phrasing. The operative text reads: "To establish that evidence is relevant, the proponent must demonstrate to the court that the trier of fact could reasonably find that the requirements of Rule 401 have been met." The court may consider the evidence itself, other evidence, and common knowledge and experience, and may admit the proposed evidence on the condition that further proof be introduced later.

The Advisory Committee's May 17, 2026 report explains that the amendment eliminates the unhelpful concept of conditional relevance and the confusing phrase "proof sufficient to support a finding." The committee note emphasizes that the revised standard is substantively identical to "sufficient to support a finding" under Huddleston, and that judicial screening may draw on common knowledge, contrasting a rural jury familiar with fertilizer hazards with an urban jury requiring proof. Citing Ronald Allen, The Myth of Conditional Relevance, 25 Loyola L. Rev. 871, 879 (1992), the note observes that because all relevance relies on intermediate premises, separating conditional relevance as a distinct category is analytically unsound.

What does not change

Conditional admission remains available under Rule 104(a) and (b). The package leaves Rule 901 authentication, Rule 902(13) and (14) electronic certifications, and Rule 702 expert standards intact. The division of responsibility persists: the judge screens threshold relevance, while the jury determines whether the defendant controlled the wallet.

The Judge and Jury Map for Attribution Evidence

Exchange records

Exchange records connect account holders to addresses. Under Rule 901, the court screens whether evidence is sufficient to support a finding of authenticity, a jury-side standard. A qualifying Rule 902(13) certificate lets the proponent skip live authenticating testimony once the judge finds the certification requirements met under Rule 104(a); the opponent may still contest authenticity to the jury. Whether the verified account holder executed the withdrawal is a further Rule 104(b) question.

Device artifacts

Forensic extractions link seized hardware to individuals. The judge screens extraction authenticity under Rule 901 or evaluates a Rule 902(14) data certificate under Rule 104(a). Whether the defendant possessed the device during operative periods, whether recovery phrases reconstruct target keys, and whether device access equated to control are conditional facts for the jury under Rule 104(b).

Signed messages

Cryptographic signatures establish key control. Under Rule 901, the judge screens whether the proof is sufficient to support a finding that the signature was generated by the target key. Genuineness is for the jury. Whether key control at signing also proves control on the contested transfer dates is a further Rule 104(b) question.

Admissions

A party's statements admitting wallet control bypass technical tracing. The judge resolves admissibility under Rule 104(a) by a preponderance of the evidence, including qualification under Rule 801(d)(2). The jury assesses the credibility, weight, and context of the admission.

Transaction patterns

Clustering heuristics represent circumstantial attribution. The judge evaluates expert methodology under Rule 702 and Rule 104(a) for reliability. Whether clustered addresses share common control, and whether that controller is the defendant, are conditional relevance issues for the jury under Rule 104(b).

A Worked Hypothetical: The Withdrawal That Names the Defendant

Hypothetical example: Defendant is sued for diverting corporate funds. Plaintiff's expert links address 1A2b...c3 to $250,000 withdrawn from Defendant's verified account at Exchange Co., tracing three transfers to a hardware wallet whose seed phrase was found in a password manager on Defendant's phone. Defendant argues KYC records do not prove who initiated withdrawals, clustering can misattribute addresses, and family members accessed the phone.

The court admits exchange records without live testimony based on a Rule 902(13) certification, an admissibility question resolved under Rule 104(a). Threshold authenticity of the phone extraction under Rule 901 survives judicial screening because proof supports a reasonable finding of authenticity. The clustering opinion survives Rule 702 scrutiny because the methodology is validated, an issue resolved by a preponderance under Rule 104(a). The attribution links are conditional facts under Rule 104(b): the court admits each because a reasonable jury could find control, instructing under Rule 105: "You may consider the exchange records and tracing evidence only for the purpose of deciding whether Defendant controlled the addresses. If you find he did not, you must disregard them on that question."

Under the proposed amendment, the substantive result is identical. The revision removes the conditional-relevance label and ties the screening test to Rule 401. Under either version, links no reasonable jury could credit are excluded, making foundation decisive regardless of terminology.

Foundation Checklist for Attribution Evidence

1. Map the chain: categorize each link as a Rule 104(a) preliminary question, a Rule 104(b) conditional fact, a Rule 901 authenticity screen, or a Rule 702 methodology review.
2. Offer conditional links subject to connecting proof under Rule 104(b), identifying evidence supplying the predicate.
3. Authenticate electronic records efficiently. Certifications under Rule 902(13) and (14) satisfy threshold authenticity without live testimony once the court confirms compliance under Rule 104(a).
4. Restrict expert testimony to forensic observations. Testifying that records associate an address with an account survives scrutiny; whether the defendant controlled the wallet is a Rule 104(b) question for the jury.
5. Request limiting instructions under Rule 105 when conditional evidence is received, defining the restricted purpose on the record.
6. Anticipate sufficiency challenges on each link, especially temporal gaps between exchange transactions, device seizures, and disputed transfers.
7. Protect criminal defendants under Rule 104(d), avoiding cross-examination beyond preliminary matters when testifying on foundation.
8. Monitor the rulemaking docket. Argue the December 1, 2024 text in active cases while tracking the proposed amendment toward its projected December 1, 2028 effective date.

Limitations

This article addresses evidentiary screening standards and judge-jury allocations under the Federal Rules of Evidence; it does not evaluate ultimate burdens of proof or displace comprehensive hearsay, authentication, and Daubert analyses. Proposed amendments remain subject to revision during public comment. State courts, including Missouri courts applying rules modeled on federal practice, are not bound by federal amendments and must be analyzed under local authority. Case outcomes turn on specific records and judicial practices. Nothing here constitutes legal advice.

Frequently Asked Questions

Q: If Rule 104(b) is amended, will the jury decide wallet ownership?

A: Yes. Under both current Rule 104(b) and the proposed revision, the judge decides only whether a reasonable jury could find the conditional fact, such as key control. The proposal eliminates conditional-relevance terminology, but the Advisory Committee note confirms the revised standard is substantively identical under Huddleston. The judge-jury allocation remains unchanged.

Q: What is the difference between Rule 104(a) and Rule 702 for blockchain experts?

A: Rule 104(a) provides the general standard for preliminary questions of admissibility, qualification, and privilege under a preponderance standard. Rule 702 governs expert testimony specifically, requiring proof of reliability by a preponderance. Expert qualifications and methodology are judge questions under Rules 104(a) and 702; whether the defendant controlled the wallet is a conditional fact for the jury under Rule 104(b).

Q: When will the proposed Rule 104 amendment take effect?

A: The amendment remains a proposal open for comment through February 15, 2027. If the Standing Committee, the Judicial Conference, and the Supreme Court approve it and it is transmitted to Congress by May 1, 2028, it is projected to take effect December 1, 2028, absent congressional action. Federal practice remains governed by the December 1, 2024 rules.

Q: Does the proposal change how blockchain records are authenticated?

A: No. The August 2026 preliminary draft addresses Rule 104 and Rule 902(1). It leaves Rule 901 authentication, Rule 902(13) and (14) electronic certifications, and Rule 702 intact. Rule 901 continues to require evidence sufficient to support a finding of authenticity, which the judge screens under the 104(b) standard before the jury evaluates genuineness.

Q: What should litigators do now when preparing wallet attribution evidence?

A: Litigators should build foundations under current rules while structuring chains to satisfy either standard: map each link, separate Rule 104(a) legal determinations from Rule 104(b) jury questions, secure Rule 902(13) and (14) certifications for digital records, and confine expert opinions to forensic findings rather than ownership conclusions.

Every case turns on its own evidentiary chain, and consultation on specific records is essential. We provide blockchain tracing, evidence review, and expert witness services for complex digital asset litigation. Review our methodology to learn how analyses are documented for courtroom presentation, or contact us to discuss a pending matter.