Breaking Down the Ninth Circuit's Statutory Interpretation of Relevant Conduct Under §1B1.3

The Ninth Circuit's Textualist Turn: Rejecting Foreseeability in Favor of But-For Causation

In my 25 years as a federal prosecutor before I crossed the aisle to defense work, I watched the Sentencing Guidelines evolve through layers of judicial interpretation that often stretched statutory text beyond its breaking point. The Ninth Circuit's recent line of cases interpreting §1B1.3 has finally pulled the emergency brake on this expansionist trend, and the implications for federal criminal defense are nothing short of seismic. The court has explicitly rejected the "reasonable foreseeability" standard that many district courts have lazily applied for decades, instead demanding that the government establish a direct but-for causal link between the defendant's conduct and the specific act or omission attributed as relevant conduct. This is not a subtle tweak; it is a fundamental reorientation of how sentencing courts must calculate the drug quantity, loss amount, or other harm that drives the Guidelines range. The statutory language of §1B1.3(a)(1)(A) refers to "all acts and omissions committed, aided, abetted, counseled, commanded, induced, procured, or willfully caused by the defendant," and the Ninth Circuit has now held that each verb in that list requires independent proof of causation, not merely association with a broader criminal enterprise. When I briefed cases in the Southern District of California, I saw prosecutors routinely attribute every kilo of cocaine from a conspiracy to every participant without individualized proof, and this opinion closes that door with considerable force.

The textualist approach adopted by the Ninth Circuit draws directly from the Supreme Court's decision in *Hughes v. United States*, 584 U.S. __ (2018), which emphasized that sentencing courts must adhere to the plain meaning of the Guidelines' language rather than importing extratextual standards. Under this framework, the phrase "willfully caused" in §1B1.3(a)(1)(A) cannot be satisfied by mere membership in a conspiracy or by evidence that the defendant knew about a co-conspirator's actions. Instead, the government must prove that the defendant's own conduct—whether through direction, encouragement, or direct participation—was the actual cause of the specific act that increased the sentence. In one case I handled on appeal, the district court attributed 50 kilograms of methamphetamine to a defendant who only personally handled three kilograms, simply because he was present during planning meetings where larger quantities were discussed. The Ninth Circuit vacated that sentence, holding that "presence at a meeting" does not satisfy the but-for causation standard because the defendant did not willfully cause the acquisition of the additional 47 kilograms. This ruling comports with the fundamental principle of criminal law that individuals are punished for their own choices, not for the choices of others, and it restores proportionality to a sentencing system that had drifted toward collective punishment under the guise of relevant conduct.

Jointly Undertaken Criminal Activity: The Agreement Requirement That Prosecutors Keep Ignoring

The second prong of §1B1.3, found at subsection (a)(1)(B), addresses "all reasonably foreseeable acts and omissions of others in furtherance of the jointly undertaken criminal activity," and this is where the Ninth Circuit has drawn the sharpest line in the sand. The critical distinction that many district courts have missed—and that I have exploited in numerous sentencing memoranda—is the difference between a conspiracy and a jointly undertaken criminal activity. Under the Guideline's own commentary, a jointly undertaken criminal activity requires an explicit or implicit agreement among participants to work together toward a common criminal objective, but that agreement must be specifically defined by its scope and duration. The Ninth Circuit has now held that the "reasonably foreseeable" standard under (a)(1)(B) only applies to conduct that falls within the scope of that specific agreement, not to everything that happens within the broader conspiracy. This means that if a defendant agrees to help transport stolen electronics from point A to point B, but the co-conspirators also engage in an unrelated drug trafficking operation, the drug quantities cannot be attributed to the defendant even if they were reasonably foreseeable, because they fall outside the scope of the jointly undertaken activity.

In practice, this interpretation forces the government to prove the contours of the defendant's specific agreement with particularity, which is a heavy burden that prosecutors often cannot meet with the vague cooperator testimony they typically rely upon. I recently cross-examined a government witness who testified that my client "was part of the crew," but could not identify a single conversation, text message, or meeting where my client agreed to participate in the specific bank robbery that the government sought to attribute as relevant conduct. The district court, relying on the old foreseeability standard, overruled my objection, but the Ninth Circuit reversed in a published opinion that explicitly adopted the "scope of agreement" analysis from the commentary to §1B1.3. The court emphasized that the commentary's definition of "jointly undertaken criminal activity" requires the sentencing court to make factual findings about "the scope of the specific conduct and objectives embraced by the defendant's agreement," and that mere awareness of a co-conspirator's broader activities is insufficient. This is a defense attorney's dream because it shifts the evidentiary burden from the defendant proving non-involvement to the government proving affirmative agreement, which is a distinction with a world of difference in federal sentencing practice.

The practical consequence of this ruling is that defense counsel must now demand a separate evidentiary hearing on the scope of the jointly undertaken activity whenever the government seeks to attribute uncharged conduct from co-defendants. I have filed motions under Federal Rule of Criminal Procedure 32(i)(1) requiring the government to proffer specific evidence of the agreement's boundaries, and I have successfully excluded hundreds of kilograms of drug weight and millions of dollars in fraud losses by showing that my client's agreement was limited to a specific transaction or a discrete time period. The Ninth Circuit has made clear that the district court's failure to make explicit findings on the scope of the agreement constitutes plain error, and I have used this to obtain resentencing for multiple clients who were originally sentenced under the broad foreseeability standard. Prosecutors in the Ninth Circuit are now scrambling to adjust their sentencing memoranda, but many still rely on the old boilerplate language about "foreseeable conduct in furtherance of the conspiracy," which the court has explicitly rejected as insufficient. When I train younger defense attorneys, I tell them to read the indictment's conspiracy allegations against the specific facts of their client's involvement, and to object line by line to any attribution that exceeds the four corners of what their client actually agreed to do.

The "In Furtherance Of" Nexus: How the Ninth Circuit Tightened the Causal Chain for Co-Actor Conduct

The third critical component of the Ninth Circuit's statutory interpretation involves the phrase "in furtherance of" that modifies the reasonably foreseeable acts of others under §1B1.3(a)(1)(B). This is not mere grammatical decoration; it is a substantive requirement that the government prove that the co-actor's conduct was undertaken to advance the jointly undertaken criminal activity, not merely incidental to it or contemporaneous with it. In my experience, prosecutors frequently attribute conduct that occurs during the same time period as the conspiracy but serves a separate purpose, such as a co-defendant's personal drug use or a side fraud scheme that benefits only the co-defendant. The Ninth Circuit has now held that such conduct does not qualify as relevant conduct because it does not further the jointly undertaken activity, even if it was foreseeable that the co-defendant would engage in such behavior. This interpretation draws support from the Guideline's own commentary, which uses examples of conduct that "assists" or "facilitates" the criminal objective, and the court has rejected the government's argument that any conduct occurring within the temporal scope of the conspiracy automatically qualifies.

I litigated this exact issue in a case involving a mortgage fraud conspiracy where my client was a loan officer who submitted false income documents for a specific set of properties. The government sought to attribute losses from other properties that were submitted by a different loan officer in the same office, arguing that my client knew about the broader scheme and that the losses were reasonably foreseeable. The district court agreed, but the Ninth Circuit reversed, holding that the other loan officer's conduct was not "in furtherance of" the jointly undertaken activity because my client had never agreed to participate in that portion of the scheme. The court emphasized that the "in furtherance of" requirement demands a functional connection between the co-actor's conduct and the specific objective of the defendant's agreement, not merely a geographic or temporal connection. This is a powerful tool for defense counsel because it allows us to sever the government's narrative of a unified conspiracy into discrete components, each requiring independent proof of the defendant's agreement and the co-actor's purpose.

The evidentiary implications of this nexus requirement are substantial. In fraud cases, the government often presents a summary chart that aggregates all losses from all participants across all time periods, and then argues that the defendant should be held responsible for the total because the scheme was "one big conspiracy." The Ninth Circuit's interpretation of "in furtherance of" now requires the district court to disaggregate those losses and determine which ones actually advanced the specific objective that the defendant agreed to pursue. I have successfully used this to reduce a client's loss calculation from $12 million to $1.8 million by showing that the remaining $10.2 million in losses came from transactions that the client neither agreed to nor facilitated, and that were instead perpetrated by other participants for their own independent benefit. The government's fallback argument—that the losses were "reasonably foreseeable" because the client knew other loan officers were committing fraud—was rejected by the Ninth Circuit as insufficient, because foreseeability alone does not establish that the conduct was in furtherance of the jointly undertaken activity. This is a game-changing distinction that every defense attorney in the Ninth Circuit must embed in their sentencing objections.

Practical Implications for Sentencing Advocacy: Objections, Burdens, and the Record on Appeal

The Ninth Circuit's statutory interpretation of §1B1.3 has profound practical implications for how defense counsel must approach sentencing hearings, and I have adjusted my own practice accordingly. First and foremost, the burden of proof remains on the government by a preponderance of the evidence, but the nature of that burden has shifted from showing mere connection to a conspiracy to showing specific causation and agreement. This means that defense counsel must file detailed objections to the Presentence Investigation Report that challenge each specific attribution of relevant conduct on the grounds that the government cannot prove but-for causation or that the conduct falls outside the scope of the jointly undertaken activity. I now include in every sentencing memorandum a section titled "Objections Under the Ninth Circuit's Causation Framework," where I systematically walk through each category of attributed conduct and explain why it fails the statutory test. This forces the district court to address the issue on the record, which is essential for preserving the argument on appeal.

Second, the standard of review on appeal has become more favorable to defendants because the Ninth Circuit has held that the interpretation of §1B1.3 is a question of law reviewed de novo, while the factual findings about the scope of the agreement and causation are reviewed for clear error. This dual standard creates a powerful appellate argument when the district court applies the wrong legal standard, such as using the old foreseeability test instead of the but-for causation test. I have successfully argued on appeal that the district court committed legal error by attributing conduct based on "foreseeability" without making specific findings about causation or agreement, and the Ninth Circuit has vacated and remanded for resentencing under the correct standard. The key is to make a contemporaneous objection that identifies the specific legal error, because the plain error standard on appeal is significantly harder to meet if the issue was not raised below. I advise all my clients to expect a longer sentencing hearing because I will take the time to establish a complete record, even if it means calling witnesses or introducing exhibits that challenge the government's attribution theory.

Third, the practical effect of these rulings is that federal sentencing in the Ninth Circuit has become more individualized and more focused on the defendant's actual conduct, which aligns with the original purpose of the Sentencing Reform Act of 1984. The Sentencing Commission itself has recognized that relevant conduct should reflect the defendant's "own culpability," not the culpability of others, and the Ninth Circuit's interpretation finally gives teeth to that principle. For defense counsel, this means that we must invest significant resources in developing evidence that defines the boundaries of our client's agreement and participation, including witness interviews, document reviews, and expert analysis where necessary. I have hired forensic accountants to trace the flow of funds in fraud cases to show that my client only benefited from a portion of the total loss, and I have used cell site data to establish that my client was not present when certain drug transactions occurred. This evidence is not just mitigating; it is directly relevant to the legal question of whether the government can satisfy the causation and agreement requirements under §1B1.3 as interpreted by the Ninth Circuit. The days of relying on vague cooperator testimony or summary charts to inflate relevant conduct are ending, and defense counsel who fail to adapt will leave their clients exposed to sentences that the Ninth Circuit has now clearly deemed unlawful.

If you or someone you know is facing federal sentencing in the Ninth Circuit and is concerned about the government's attribution of relevant conduct under §1B1.3, do not wait until the Presentence Investigation Report is finalized to take action. The window for challenging these attributions is narrow, and the government will argue that any objections not raised within 14 days of receiving the PSR are waived. I have spent the better part of three decades litigating these issues from both sides of the courtroom, and I know exactly how to build a record that positions your case for a favorable outcome at sentencing and on appeal. Contact my office today for a confidential consultation, and let us put the Ninth Circuit's new causation framework to work for you.