Custodia's master account fight reaches the Supreme Court, with the industry piling in behind it

The Blockchain Association filed an amicus brief this week supporting Custodia Bank's petition for Supreme Court review of the Federal Reserve Bank of Kansas City's refusal to give it a master account ^[1]. The question is not really about crypto: it is whether a regional Reserve Bank holds discretion to reject an application from an eligible, state-chartered depository institution, or whether the Monetary Control Act of 1980 obliges it to provide the service ^[2][7].

The procedural history explains why this has become a constitutional-flavoured dispute rather than a licensing complaint. Custodia, a Wyoming special-purpose depository institution founded by Caitlin Long to serve digital-asset clients, applied to the Kansas City Fed in October 2020 ^[3]. The application was denied in January 2023, on risks the Reserve Bank tied to Custodia's crypto-oriented business model ^[5] - roughly 27 months after it was filed ^[6]. A district court ruled against the bank in 2024 ^[8]. A divided Tenth Circuit panel affirmed in late 2025, holding that Reserve Banks retain discretion to approve or deny ^[9]. The full appeals court declined en banc rehearing 7-3 in March 2026 ^[10], and Custodia petitioned the Supreme Court last month ^[11]. That is close to six years from application to certiorari petition ^[12].

What is at stake operationally is settlement. A master account is direct access to the Fed's payment systems, including Fedwire and related settlement services ^[4]. Without one, an institution runs its payments through correspondent banks, which adds cost, delay, counterparty exposure, and the standing risk that the intermediary walks away ^[13]. That last item is the one operators should read twice: the dependency is not priced, it is discretionary.

The Blockchain Association's brief argues the Tenth Circuit's reasoning hands the Fed unprecedented power and undercuts the dual banking system, in which states charter institutions alongside federal authorities ^[14]. Its sharper claim is that unchecked denial authority lets federal officials veto state-approved business models serving lawful industries ^[15]. The group points to earlier regulatory efforts that restricted banking access for digital-asset firms and warns the lower-court logic could be reused against other disfavoured sectors without meaningful oversight ^[16]. On the Fed's partial workarounds, the brief is dismissive: narrower payment accounts are described as inadequate substitutes for full master-account privileges ^[17]. A limited-purpose arrangement recently granted to another crypto-related firm shows pathways exist but remain constrained ^[18].

Two things to watch. The Kansas City Fed has until mid-September to respond to the petition ^[19], and the shape of that response - jurisdictional, statutory, or a mootness play built on the narrower account options - will tell you how confident the Reserve Banks are in the discretion the Tenth Circuit gave them. The other is the 7-3 en banc split ^[10]: three votes for rehearing is not a circuit in agreement with itself, which is the sort of detail that moves a cert petition from long shot to live. Custodia's own charter status is now secondary. Any ruling would set the terms on which state-chartered banks reach the national payments system, and how far federal agencies may go in managing perceived risk ^[20].