Digital Euro Systemic Liquidity Reallocation - Legal Constraints Spain / ECB

This is the most complex legal issue in EU monetary law today. The question: If Europeans move €700 billion from bank deposits into Digital Euro wallets, banks lose funding to give loans. How can ECB legally prevent systemic bank run without violating Treaty?

I. WHAT IS SYSTEMIC LIQUIDITY REALLOCATION?

Digital Euro is not a crypto. It is central bank money - direct liability of ECB and Banco de España, like cash but digital.

Current system: Your €10,000 in Santander is commercial bank money - Santander's promise. It uses it to lend. If you withdraw to Digital Euro, you convert commercial money to central bank money. Santander loses €10,000 of cheap retail funding, must replace with expensive wholesale funding or ECB funding.

ECB simulations: €739 billion in deposit outflows if holding limit is €3,000 per person. Copenhagen Economics study confirms. ECB itself acknowledges risk.

ECB calls it two risks:

1. Deposit flight / Bank run risk - in crisis, everyone moves to Digital Euro instantly (faster than 2008 ATM queues).
2. Structural disintermediation - banks permanently lose role of channeling public savings into loans and credit.

Digital euro wallets create deposit mobility at scale. Even moderate migration could reduce banks' low-cost retail funding and increase reliance on wholesale markets. Without automated liquidity controls, banks risk margin erosion.

II. LEGAL BASIS FOR DIGITAL EURO - Can ECB Even Issue It?

Article 128(1) TFEU: "The European Central Bank shall have the exclusive right to authorise the issue of euro banknotes within the Union. Such notes shall be the only such notes to have the status of legal tender."

ECB's legal argument: Digital Euro is equivalent to banknotes - Article 128(1) TFEU provides ECB with right and task to issue legal tender. This right is given exclusively to central banks. Therefore ECB is both entitled and obliged de lege lata to issue digital euro on basis of article 128 TFEU.

Regulation COM(2023) 369 final - European Commission proposal 28 June 2023: Digital Euro Regulation.

Art 4(1): "In accordance with the Treaties, the European Central Bank shall have exclusive right to authorise the issue of the digital euro."

Status:

• Legal tender status - digital euro will have legal tender status in EU, equivalent to cash. Means one euro is worth one euro - whether digital euro, coins or banknotes.
• Cannot be programmable: Current draft law expressly prohibits digital euro from being programmable or having use limited. ECB defines digital euro as "money, not a coupon." Under no circumstances will it have expiration date; its use will not be subject to restrictions. Issuer cannot limit what products can be purchased.

III. LEGAL CONSTRAINTS TO PREVENT LIQUIDITY REALLOCATION

ECB cannot just say "trust us". EU law requires proportionality. Constraints must be in Regulation itself:

1. Holding Limits - The Core Tool

For individual users, cap of around €3,000 per person is under consideration to prevent destabilisation of bank funding. For merchants, ECB has confirmed zero holding limit: businesses will not be permitted to store Digital Euros and will be required to convert them back into traditional bank money after each transaction. This ensures Digital Euro does not compete directly with commercial liquidity pools.

• Retail: €3,000 per citizen (Parliament proposing €3,000-€4,000)
• Merchants: €0 - auto-sweep to bank account.
• Legal persons: Proposed bar on holding by non-financial corporates to prevent concentrated liquidity shifts during market volatility.

Legally: Holding limits must be set by delegated act of ECB, not fixed in Regulation, to adapt over time.

2. No Remuneration

Digital Euro balances will have zero interest - no interest on digital euro balances. Prevents it being savings product competing with bank deposits.

3. Reverse Waterfall Mechanism

ECB is exploring reverse waterfall mechanism, under which excess digital euro balances could be automatically swept back into users' commercial bank accounts. If you receive €5,000 but limit is €3,000, €2,000 auto-moves to your Santander account. Also waterfall in reverse: if you need to pay €4,000 but only have €2,000 digital euro, rest auto-drawn from bank account.

Legal status: Must be mandated that digital euro accounts linked to commercial bank accounts.

4. Distribution Through Banks

Digital euro would be distributed through banks and other supervised intermediaries, holdings would not be remunerated and would be subject to holding limits, and wallets could be linked to commercial bank accounts. ECB will not have access to personal data; only regulated intermediaries will manage limited identity information.

Legally prevents disintermediation - banks keep client relationship.

5. Proportionality Test under EU Law - Gauweiler / Weiss

This is where case law matters.

IV. CASE LAWS - How Courts Will Judge Digital Euro Limits

CASE 1: Gauweiler C-62/14 (OMT Program) 2015 - The Mandate Test

German citizens challenged ECB's Outright Monetary Transactions (whatever it takes). German Constitutional Court referred to CJEU.

CJEU: Confirmed OMT complied with EU Treaties because it was necessary and proportionate measure to restore functioning of monetary policy transmission channels. Court says assess whether ECB measure falls within scope of mandate requires analysis of specific objectives pursued, rather than effects.

Relevance to Digital Euro: ECB must prove holding limits pursue monetary policy objective (preserve transmission channel - banks must be able to lend), not just fiscal policy. If ECB sets €3,000 limit, it must justify it is proportionate to preserve financial stability. If limit too low, it kills usability of digital euro - disproportional.

CASE 2: Weiss C-493/17 (PSPP) 2018 - Proportionality Strict

Challenge to Public Sector Purchase Programme (QE). German Constitutional Court said PSPP violates proportionality and exceeds ECB mandate.

CJEU: PSPP is proportionate measure of monetary policy, within ECB's powers, provided specific features prevent monetary financing under Art 123 TFEU.

German Federal Constitutional Court (BVerfG) 5 May 2020 then rejected Weiss - said CJEU lacked proportionality analysis. Historic clash.

Relevance: Digital Euro holding limits will face same challenge in Karlsruhe. Banks or citizens will claim ECB exceeded Art 127-128 TFEU by creating instrument that changes financial structure. CJEU will apply Weiss test: Is Digital Euro (a) suitable to achieve monetary sovereignty objective (b) necessary (c) does not have manifestly disproportionate effects on banks?

If ECB sets limit at €0 for merchants and €3,000 for citizens, it will argue necessary to avoid systemic threat to bank balance sheets - effect marginal, does not pose systemic threat given aggregate LCR of banks under ECB supervision stood at 153.9% at end Q1 2026.

CASE 3: Spanish Specific - Banco de España Authority

Under Law of Autonomy of Banco de España, Banco de España shall, with prior authorisation of ECB, have power to issue euro banknotes. For digital euro, Spanish transposition law (draft law on digitalisation and modernisation of financial sector) modifies scope to include payment operators. Article 3(1) Law 21/2011 defines e-money institutions, Article 4 says Banco de España is responsible for authorising.

In Spain, Royal Decree-Law 8/2023 enforces DORA for payment operators - Banco de España is competent authority. Same authority will supervise digital euro distribution.

No Spanish Supreme Court case yet on digital euro, but Spanish banks face tighter rules - Banco de España does not set cash withdrawal limit, but banks cap daily card withdrawals around €600 to guard against theft. Same logic will apply to digital euro - legal to hold, but operational limit by intermediaries.

CASE 4: Pringle C-370/12 - Monetary vs Economic Policy

CJEU distinguished monetary policy (ECB competence) vs economic policy (Member States). Digital Euro must be classified as monetary policy, not economic policy, otherwise requires unanimity under Art 136 TFEU. Holding limits help - they show objective is to protect monetary transmission, not to fund governments.

V. SPAIN'S SPECIFIC LEGAL CONSTRAINTS

Legal Tender Obligation: In Spain, merchants must accept legal tender. If digital euro has legal tender status, Spanish merchants must accept it - but with zero holding limit, they must immediately convert. Royal Decree will need to amend Art 1170 Civil Code.

Financial Inclusion: Spanish law requires access to payment accounts (RDL 19/2017). Digital euro must be accessible offline for rural areas in Galicia, etc. - current draft requires offline functionality.

Data Protection: EDPB says digital euro will be assimilated to euro banknotes, but ECB will not have access to personal data - only intermediaries. Spanish AEPD will enforce. High privacy model required under LOPDGDD.

Banking Law: Spanish Law 10/2014 on credit institutions - if deposits fall 10-15% due to digital euro, banks must increase HQLA - weigh on profitability. Banco de España stress tests: anticipated impact marginal, does not pose systemic threat.

Conclusion Legal Framework:

Digital Euro is legally possible under Art 128(1) TFEU, but systemic liquidity reallocation must be constrained by 4 legally binding mechanisms: holding limits, zero remuneration, zero holding for merchants, reverse waterfall. These constraints are not technical options - they are legal proportionality requirements from Gauweiler/Weiss to survive challenge before CJEU and German Constitutional Court.

For Spain, distribution via Banco de España authorised intermediaries, with Banco de España as overseer, and compliance with DORA and PSD2.