US Moves to Exclude DeFi Defense as Ethereum MEV Exploit Case Nears Retrial

Federal prosecutors are trying to block a key DeFi industry brief from the courtroom. The move comes as a landmark case involving alleged Ethereum Maximal Extractable Value (MEV) exploitation heads toward a do-over.

The Regulatory Squeeze

The Department of Justice isn't just prosecuting individuals—it's attempting to sideline an entire sector's perspective. By seeking to exclude the DeFi-focused amicus brief, regulators aim to frame the complex technical debate on their own terms. It's a classic legal maneuver: control the narrative, control the outcome.

MEV in the Crosshairs

At the heart of the retrial is MEV—the profit validators can make by reordering, inserting, or censoring transactions within a block. The prosecution alleges exploitation, while the defense argues it's an inherent, if controversial, feature of blockchain mechanics. Without the DeFi brief, the jury might only hear the government's simplification of a billion-dollar ecosystem.

A Precedent in the Making

This retrial isn't just about one case. It's a battleground for defining legal boundaries around decentralized finance. A conviction could empower regulators to pursue similar actions across the crypto landscape, chilling innovation under the familiar guise of investor protection—because nothing protects profits like stifling competition.

The courtroom clash exposes a widening rift: technologists building autonomous systems versus regulators clinging to analog-era frameworks. As the retrial looms, the outcome could either validate DeFi's novel structures or hand authorities a blueprint for dismantling them. After all, what's a financial revolution without a few government attempts to shut it down?

US Attorney Clayton raised concerns about DEF’s amicus brief

In a statement, US Attorney Clayton argued that DEF’s amicus brief, which is disconnected from the trial record, restates some legal claims that the court has already rejected.

He further explained, “Since the Court has already made decisions on the legal matters discussed in the amicus brief and DEF does not provide any new information relevant to the current motion, their submission is unlikely to help the Court in considering these specific issues [related to a motion for acquittal].” 

Considering the intense nature of the situation, reports dated November noted that Judge Clarke declared a mistrial just after jurors found it difficult to decide whether the two brothers should be pronounced guilty or not guilty. 

Regarding the case raised against the brothers, sources close to the situation claimed that they were accused of inappropriately utilizing automated maximal extractable value (MEV) bots for their own benefit. Later in the week, the US government requested that the court consider setting a retrial date for either late February or early March 2026. 

At this point, a draft representing the DEF brief, issued on December 19, illustrated that the organization supported the motion to clear or withdraw the claims against the two brothers. According to them, the case presented significant consequences for the industry.

DEF further commented on the matter, stating that, “[P]rosecutions like this one create confusion and fear among software developers, discouraging involvement in DeFi and pushing participants to other countries”. They added, “The DOJ should not rush into indictments based on misinterpretations of current laws, as this will hinder growth by creating uncertainty about the rules.” 

Uncertainties surrounding the two brothers’ fate raise controversy in the ecosystem 

The announcement regarding the US government’s opposition to the Defi Education Fund’s brief prompted several reporters to reach out to the organization for comment on the situation. However, it declined to respond.

Even with this decline, analysts noted that several individuals in the crypto industry are still paying close attention to the possibility of how this case could impact MEV-related activities. The individual adopted this move at a time when uncertainties surrounding the fate of the Peraire-Bueno brothers grew intense.

Meanwhile, reports unveiled that Coin Center, a leading non-profit research and advocacy center focused on crypto-related matters, issued an amicus brief during the criminal trial. Sources claimed that this brief opposed the US government’s outlook. As a result, prosecutors requested the court to discard the brief.

On the other hand, another reliable source disclosed that the two brothers initially encountered allegations including conspiracy to commit wire fraud, money laundering activities, and conspiracy to acquire stolen property. With these claims in place, they noted that if, by any chance, the brothers undergo a retrial on these similar allegations and are found guilty, they could be subjected to a prison sentence of up to 20 years for each count.

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