Two developers faced trial over four words in a regulatory framework dating to the 1970s: what counts as transmitting money. The answer will determine whether writing DeFi code constitutes a regulated financial business or protected publishing — and Section 604 of the CLARITY Act is Congress's attempt to settle the question by statute.

A money transmitter is a business that accepts currency or value from one person and transmits it to another person or location. Under the Bank Secrecy Act, transmitters are regulated financial institutions with anti-money-laundering obligations, and operating one without the necessary licenses is a federal crime under 18 U.S.C. Section 1960.

The definition was originally built for companies like Western Union and was applied to crypto through FinCEN's 2013 guidance, which placed exchanges, custodial wallets, and payment processors squarely inside the regulatory perimeter — licensed state by state across 49 states.

The unresolved issue is non-custodial software. FinCEN's 2019 guidance was widely read to exempt developers whose code never gives them independent control over user funds — until the Tornado Cash and Samourai Wallet prosecutions advanced the opposite theory.

The resulting question — can you transmit money you never control? — is the sharpest legal dispute in crypto today, pitting prosecutors' interest in preserving enforcement tools against the industry's argument that regulating code amounts to regulating speech. The stakes are not purely domestic: the European Union's Markets in Crypto-Assets Regulation (MiCA), fully applicable since December 2024, already excludes services provided in a fully decentralized manner without intermediaries, meaning the line Section 604 proposes is one other major jurisdictions have begun to draw.

Section 604 of the CLARITY Act would resolve this by statute, shielding non-custodial developers from money-transmitter status. That is why district attorneys' associations oppose the provision, and why its final wording may matter as much as the bill's passage.

The category and its machinery

Most legal categories in crypto remain abstractions until they are not. The money transmitter category became concrete the day federal agents arrested the developers of privacy software, charged them with operating an unlicensed money transmitting business, and signaled that the government's reading of a 1970s-era definition now extended to people who wrote code and never touched a customer's coin.

The category has been the quiet workhorse of American crypto regulation for a decade. It explains why exchanges hold 49 state licenses, why kiosks register with FinCEN, and why every custodial app operates an anti-money-laundering program. Through the Tornado Cash and Samourai Wallet prosecutions, it has also become the industry's sharpest legal question: can you transmit money you never control?

In the working federal definition, a money transmitter is a person or business that provides money transmission services — accepting currency, funds, or other value that substitutes for currency from one person, and transmitting it to another location or person by any means. The definition's breadth is deliberate. It was designed to cover Western Union and its descendants: wire services, remittance shops, payment processors — any business whose core product is moving other people's money. The phrase "other value that substitutes for currency" later became the hinge that swung crypto inside the perimeter.

Being a transmitter carries two distinct regulatory burdens, and conflating them creates downstream confusion. The first is federal: under the Bank Secrecy Act of 1970, as expanded by the Patriot Act, money transmitters are a category of money services business (MSB) regulated by FinCEN, the Treasury bureau that administers American anti-money-laundering law. An MSB must register with FinCEN, build and maintain an AML compliance program, file suspicious activity and currency transaction reports, keep records, and comply with sanctions administered by OFAC. The BSA's design is one of deputization: financial institutions serve as the surveillance and reporting layer of law enforcement, and transmitters are drafted into that role.

The second burden is state-level. Forty-nine states — all except Montana — separately require money transmitter licenses, each with its own application, bonding, capital, and examination regime. This is the notorious state-by-state maze that costs a national crypto business years and millions of dollars to navigate, and which federal charters and preemptive legislation are perennially pitched as a way to escape.

Behind both layers sits the enforcement mechanism that gives the category its teeth: 18 U.S.C. Section 1960, which criminalizes operating an unlicensed money transmitting business. Section 1960 is why the definition's boundary is not merely academic. Classification as a transmitter without licenses is not a compliance gap to remediate — it is a potential indictment, and the statute's reach, covering businesses that fail state licensing, fail FinCEN registration, or transmit funds known to be criminally derived, has made it the charge of choice in crypto cases.

Who is clearly inside

For most of the crypto stack, the classification analysis has been settled since FinCEN's foundational 2013 guidance, which declared that administering or exchanging virtual currency constitutes money transmission like any other — virtual currency and fiat are subject to the same rules.

Exchanges are transmitters: they accept value from customers and transmit it between users, between currencies, and out to wallets. Custodial wallet providers are transmitters, because holding users' keys and moving funds at their instruction is the definition performed literally. Payment processors that accept crypto on behalf of merchants, over-the-counter desks, and crypto kiosk operators — the ATM networks whose compliance failures have made them a fixture of enforcement actions and, in the pending CLARITY text, the subject of first-ever federal operating standards — are all inside.

The practical consequence is the compliance architecture that users experience without naming it: identity verification at onboarding, transaction monitoring, withdrawal reviews, and the entire know-your-customer apparatus. This exists because the BSA requires it of financial institutions, and the transmitter classification makes these businesses financial institutions.

This half of the regulatory map is notably uncontroversial. The industry litigates many things, but the proposition that an exchange holding customer funds is a regulated transmitter is not one of them. The battle is entirely at the other edge of the category, where software performs the transmitting and no business ever holds the money.

The control question

The consensus, while it held, rested on a 2019 FinCEN guidance document that the industry treated as its constitutional framework. Synthesizing years of interpretation, the guidance was widely understood to establish that what makes a transmitter is independent control over the value being moved. Under this reading, a business that accepts and holds funds, then sends them on, transmits money. A developer who publishes software through which users move their own funds — keys in their own hands — does not. Non-custodial wallets, decentralized exchange protocols, and mixing software fell on this side of the line: their creators were publishers of tools, not operators of financial businesses. A decade of DeFi was built on that distinction.

The prosecutions shattered it. The federal cases against the developers of Tornado Cash — the Ethereum privacy protocol — and Samourai Wallet — the Bitcoin privacy wallet — advanced a theory under Section 1960 that alarmed the industry precisely because of what it did not require: custody. The government's position, as industry lawyers characterized it, defined a new class of money transmitting entities: developers of decentralized protocols where no intermediary ever controls user tokens at any stage.

If writing and maintaining software that moves value constitutes transmission regardless of who holds the keys, then the 2019 dividing line ceases to exist, and every non-custodial developer in the country carries latent criminal exposure that turns on prosecutorial discretion.

Legal scholars, including counsel writing in the Stanford Blockchain Review, framed the resulting question in its cleanest form: can you transmit money you never control? The industry's answer is no, and that the contrary theory converts code publication — an activity with First Amendment dimensions — into an unlicensed financial business. The constitutional argument draws on precedent from Bernstein v. United States, where the Ninth Circuit held that encryption source code is speech protected by the First Amendment, a ruling that privacy-software developers have invoked to argue that publishing non-custodial protocols deserves the same protection. Law enforcement's answer is that the question is too clever by half: the developers built, deployed, updated, and, in some accounts, profited from machines whose function was moving money, much of it tied to criminal activity. In their view, the custody test is a formalism that launders responsibility.

Courts have not settled the matter. The cases produced plea agreements, contested rulings, and doctrine that remains genuinely open — the worst possible state for an industry deciding where to build. The boundary of a felony is currently a litigation position.

The state layer: the maze beneath the maze

Before the statutory answer, one more layer deserves its own treatment, because the federal definition is only half of any crypto business's transmitter problem — and often the less expensive half.

Money transmission is regulated on two independent tracks, and the state track came first. Forty-nine states plus territories license transmitters under their own statutes, each with its own definition of transmission, its own exemptions, its own capital, bonding, and net-worth requirements, and its own examiners. The definitions do not align: an activity classified as transmission in one state may be exempt in another. Some states carve out closed-loop systems or agent-of-payee arrangements, and several have enacted bespoke virtual-currency regimes on top — New York's BitLicense being the most prominent, with application timelines measured in years and legal fees in the millions.

A national crypto business therefore does not ask whether it is a money transmitter once. It asks the question up to fifty times, against fifty different legal texts, and maintains the resulting license portfolio through fifty renewal and examination cycles. Industry estimates of the full build have ranged from the high seven figures into eight figures, before a single federal obligation attaches.

The maze's existence explains three otherwise puzzling features of the industry's structure. It explains the partnership model — fintechs and crypto apps riding licensed sponsors' transmitter licenses instead of acquiring their own — an arrangement whose fragility the Synapse collapse exposed from the banking side. It explains the outsized value of any federal instrument that preempts the states: the OCC trust charters at the center of the current bank-lobby fight are prized precisely because a federal charter can replace the fifty-license portfolio, which is also why state regulators, through the Conference of State Bank Supervisors, oppose them alongside the banks.

It also explains a persistent asymmetry in Section 604's politics. The provision addresses only the federal BSA definition, meaning a developer shielded federally could in principle still face state transmitter theories. However, the practical center of gravity — and the criminal exposure that made the prosecutions existential — is federal, which is why the statutory fight concentrates there.

The state layer also offers a cautionary tale. Uniformity projects, model acts, multistate licensing agreements, and examination passporting have worked at the state level for years and closed perhaps half the gap. The underlying definitional divergence persists because each legislature guards its own text. The lesson for Section 604 is direct: definitions of money transmission have never converged voluntarily at any level of American government in fifty years of trying. They converge when a superior authority writes one binding text — which is what the CLARITY provision would do, and why a paragraph of statutory language matters more, to both sides, than a decade of guidance.

Section 604: the statutory answer

This is the dispute Section 604 of the CLARITY Act exists to resolve. Understanding the provision requires understanding both what it does and the fight over its edges.

The section — descended from the Blockchain Regulatory Certainty Act that was folded into the House bill — draws the line in statute where the 2019 guidance drew it in interpretation. Developers and publishers of non-custodial software — code that never takes control of user funds — would not be classified as money transmitters under the Bank Secrecy Act by virtue of publishing or maintaining that code. The custody test becomes law rather than guidance, retroactively vindicating the industry's decade-old reading and prospectively foreclosing the Section 1960 theory on which the privacy prosecutions relied.

For DeFi, the provision approaches existential significance, which is why industry lobbying has treated its preservation in the merged Senate text as a red line. The competitive dimension sharpens the urgency: developers and capital have already migrated to jurisdictions that provide statutory clarity on non-custodial software, and the absence of an equivalent U.S. safe harbor has been a recurring argument for its passage.

The opposition is institutional and specific. The National District Attorneys Association, joined by sheriffs' and prosecutors' organizations, argues the provision would materially impair criminal investigations by severing the liability connection between protocol developers and the financial activity their code enables. That connection, they contend, provides the charge that lets investigators reach the infrastructure layer of laundering operations.

Senator Wyden's response compresses the other side to a single sentence: developers who never control customer funds should not be classified as money transmitters for publishing code. The negotiation between those positions, conducted through Senator Cortez Masto's drafting sessions, is where the provision's real content will be determined. The elements to watch are the carve-backs: language distinguishing mixers from wallets, front-end operators from contract deployers, or profiting maintainers from mere publishers would signal the compromises law enforcement extracted.

Equally important is what Section 604 does not touch. Custodial businesses remain fully inside the perimeter: exchanges, hosted wallets, processors, and kiosks retain every BSA obligation and every state license. The broader CLARITY framework separately extends bank-secrecy duties across registered digital-asset intermediaries. The provision does not deregulate crypto's financial businesses — it declines to regulate its publishers, a distinction both sides of the debate have incentives to blur.

For anyone building or operating in this industry, the practical summary is concise. If a business holds user funds, it is a money transmitter — licensed and surveilled — and nothing pending in Congress changes that. If software never holds them, its authors' status is today a contested prosecution theory and would, under Section 604, become statutory protection. The distance between those two propositions is where two developers stood trial, and where American DeFi's legal future is being drafted.

Section 1960: a historical footnote with current stakes

A historical footnote completes the picture and explains the category's peculiar gravity in crypto enforcement. Section 1960 was itself a product of a moral panic about new money technology. Congress enacted it in 1992, targeting storefront wire services suspected of laundering drug proceeds, and strengthened it during the Patriot Act era. The removal of a knowledge requirement for state-licensing violations converted it into something close to a strict-liability trap: a business that misjudges whether a state considers it a transmitter commits a federal crime by operating, regardless of what it believed.

That structure, born decades before anyone imagined non-custodial software, is what gives the current definitional fight its stakes. Most regulatory misclassifications in finance produce deficiency letters and fines. Misclassification under Section 1960 produces indictments. The statute has become the government's most flexible crypto charge precisely because its elements are so spare — no fraud required, no victims required, only transmission without a license.

The industry's decade of appeals for regulatory clarity has always been, at bottom, a plea about this statute: not for permission to operate, which custodial businesses obtain through licensing, but for certainty about which side of a criminal line an activity falls on. Section 604 is the first legislative text that would draw that line in statute rather than guidance, which is why a provision that changes no license requirement for any operating business has nonetheless become one of the most contested paragraphs in the bill.

Disclaimer: This article is for informational and educational purposes only and does not constitute financial, investment, or legal advice. It describes statutes, guidance, active litigation, and pending legislation whose interpretation and status may change. Anyone facing classification questions should consult qualified counsel. Information is accurate as of July 21, 2026.