As governments and technology providers race to deliver secure, scalable digital identity solutions, the question of interoperability looms large.
Digital Identity and the interoperability challenge
Last month’s mobile driver’s licence (mDL) interoperability test events in Utrecht, The Netherlands, marked a pivotal moment in the evolution of digital identity infrastructure — echoing familiar lessons from the world of payments.
Just as payment cards revolutionised how we transact globally, mDLs and other mobile credentials have the potential to transform how we prove who we are — in sectors ranging from travel and healthcare to financial services and retail.
But to reach that scale, digital identity systems must overcome a key barrier: the ability for credentials issued in one jurisdiction to be accepted seamlessly in another.
The Vision for Mobile Credentials
At the heart of today’s digital identity ambition is the notion of universal digital wallets — mobile-based repositories that allow individuals to present verifiable credentials on demand, in both online and offline scenarios.
In this future, a student from Tokyo should be able to walk into a pharmacy in Berlin or a bar in Melbourne and have their mDL recognised and trusted.
To get there, solutions are increasingly being developed in line with the ISO 18013 series of standards — which extend beyond driver’s licences to encompass identity cards, health passes and more under the broader concept of “mDocs”.
But while technical specifications are a starting point, standards alone are not enough.
Learning from Payments: Standards Plus Certification
The payments industry learned this the hard way.
ISO 7816 — the foundational specification for smartcards — was introduced as far back as 1987.
It laid the groundwork for today’s card networks, but it was the introduction of EMV standards and, crucially, certification programmes that enabled genuine global interoperability.
In short: every card must work at every terminal, every time.
This level of reliability was not achieved by standards alone, but by rigorous, system-wide testing against approved reference systems.
Certification became the guarantor of trust — for issuers, acquirers, merchants and consumers alike.
The Role of Testing in mDL Development
That’s why the interoperability tests in Utrecht are so significant.
They brought together dozens of global players — from wallet providers to system integrators — to validate their mDL implementations against the evolving ISO 18013 framework.
Firms like Fime contributed tools such as the Digital Identity Test Suite, offering reference implementations that simulate both wallet and verifier roles.
These weren’t theoretical exercises. They involved real (test) transactions designed to uncover gaps in how vendors are interpreting and implementing the standard.
In effect, these sessions mark the first steps toward a formal certification regime — one that will be essential to ensuring mDLs are truly interoperable across borders and sectors.
The Question of Scheme Governance
But if certification is essential, then the natural next question is: who will own the scheme?
In payments, global card networks like Visa and Mastercard became the de facto standard-bearers. In digital identity, no such global authority exists.
In the EU, the revised eIDAS regulation gives member states responsibility — a model that may work regionally, but leaves fragmentation at the global level.
Initiatives such as the WE BUILD consortium, supported by the European Commission, aim to drive cohesion — with interoperability rightly prioritised as a non-negotiable.
Ultimately, as digital identity races toward mainstream adoption, the ability to replicate payments’ interoperability success may determine which solutions survive — and which fade into fragmentation.
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