You’ve built something brilliant. A marketplace with end-to-end encryption, bulletproof anonymity, and a payment system that would make traditional banks weep. Your code is elegant, your architecture is sound, and you’ve solved problems that would stump most developers. Then one morning, law enforcement shows up at your door with a warrant, and suddenly you’re facing charges for crimes committed by people you’ve never met, using software you built in good faith.
This isn’t a hypothetical scare story. It’s what happened to Ross Ulbricht, the creator of Silk Road, who’s now serving a life sentence without parole. It’s what happened to Alexandre Cazes of AlphaBay, found dead in a Thai prison cell whilst awaiting extradition. These weren’t hardened criminals when they started writing code. They were developers who believed they were building neutral platforms, tools that could be used for good or ill, and that the responsibility lay with the users, not the creators.
They were catastrophically wrong about how criminal law works. And if you’re building anything involving marketplaces, anonymity, or cryptocurrency, you need to understand why their reasoning failed, because the gap between “innovative platform” and “criminal enterprise” is far narrower than most developers realise.
What Makes a Marketplace “Dark”?
The term “dark web” gets thrown around carelessly, but from a technical standpoint, it refers to networks that require specific software to access and that prioritise anonymity above all else. The most common is Tor, the onion routing network that bounces your connection through multiple encrypted relays, making it nearly impossible to trace. Then there’s I2P, Freenet, and a handful of others that offer similar privacy guarantees.
Building on these networks isn’t inherently illegal. Journalists use Tor to communicate with sources in authoritarian regimes. Activists use it to organise without government surveillance. Ordinary people use it because they value their privacy in an age of ubiquitous data collection. The technology itself is neutral, morally speaking.
But here’s where it gets complicated. When you build a marketplace on these networks, you’re making architectural decisions that have legal implications you might not foresee. Integrating cryptocurrency payments, particularly privacy coins like Monero, adds another layer of anonymity. Removing user verification requirements makes your platform accessible but also untraceable. Each technical choice moves you along a spectrum from “privacy-focused platform” to “purpose-built criminal infrastructure,” and the law cares very much about where you land on that spectrum.
The Criminal Law Framework
Most developers think about criminal liability in terms of direct action. You’re guilty if you personally commit the crime. This is a dangerous misunderstanding of how modern criminal law actually operates, particularly in the UK and US.
Under the UK’s Serious Crime Act 2007, you can be convicted of encouraging or assisting an offence even if the offence never actually occurs. The prosecution doesn’t need to prove you intended a specific crime to happen. They only need to show you believed your actions would assist criminal conduct and that you did it anyway. This is a much lower bar than most people realise.
In the United States, the federal aiding and abetting statute (18 USC § 2) is similarly broad. If you assist someone in committing a crime, you’re treated as a principal, not an accessory. You face the same penalties as if you’d committed the crime yourself. And “assistance” can mean providing the platform, the tools, or even the knowledge that makes the crime possible.
The doctrine of wilful blindness makes this even more treacherous. You can’t stick your head in the sand and claim ignorance when the evidence of criminal activity is obvious. If a reasonable person would have known that their platform was being used for illegal purposes, and you deliberately avoided finding out, the law treats that as knowledge. You don’t get to build plausible deniability into your business model.
Case Studies: Where Platforms Crossed the Line
Silk Road remains the textbook case of how not to build a marketplace. Ross Ulbricht didn’t merely create a platform that criminals happened to use. He actively cultivated a marketplace for drugs, fake IDs, and hacking tools. He took a commission on every transaction. He marketed the site as a place to buy illegal goods beyond the reach of law enforcement. The court found that he’d employed administrators, resolved disputes between buyers and sellers, and even allegedly arranged murders (though those charges were dropped).
The prosecution didn’t need to prove Ulbricht sold drugs himself. His role in facilitating thousands of illegal transactions was enough. He created the infrastructure, profited from it, and actively managed it. That’s not a neutral platform. That’s a criminal enterprise, regardless of how elegant the code was.
AlphaBay’s Alexandre Cazes made similar mistakes but added new ones. He accumulated spectacular wealth from commission fees on illegal transactions, then made the catastrophic error of leaving traces connecting his real identity to the site. When Thai police arrested him in 2017, they found he’d been living in a mansion bought with proceeds from the marketplace. The “neutral platform” defence crumbles pretty quickly when you’re driving a Lamborghini paid for by drug trafficking commissions.
Backpage.com offers a different lesson. It started as a legitimate classifieds site but became notorious for facilitating sex trafficking. The operators claimed they were protected by Section 230 of the Communications Decency Act in the US, which generally shields platforms from liability for user content. But prosecutors argued, successfully, that Backpage actively edited ads to conceal their illegal nature, stripping out terms that would obviously indicate prostitution whilst keeping the essential content. That crossed the line from passive hosting to active facilitation. The site’s executives faced federal charges, and the company was seized.
More recently, Tornado Cash presented a new wrinkle in this legal landscape. It’s a cryptocurrency mixer, software that obscures the origins of crypto transactions by pooling funds from multiple users. The developers argued they’d built a privacy tool that could be used legitimately. The US Treasury Department disagreed, sanctioning the service for facilitating money laundering, including for North Korean hackers. One of the developers was arrested in the Netherlands, raising urgent questions about whether writing privacy-preserving code can itself be criminal when you know it will be used for illegal purposes.
The Grey Zones Developers Face
Not every platform lands neatly on one side of the legal line or the other. Most of us operate in spaces that are genuinely ambiguous, and that ambiguity is terrifying when your freedom depends on it.
Take encrypted messaging apps. Signal and Telegram both offer strong encryption and varying degrees of anonymity. Criminals use them extensively to coordinate illegal activity. But nobody seriously argues that the developers should be prosecuted, because these platforms serve obvious legitimate purposes and the operators don’t profit from criminal use. They’ve built tools, not marketplaces.
Peer-to-peer marketplaces present trickier questions. If you create a decentralised platform where users transact directly without your involvement, are you liable for what they sell? The honest answer is that it depends on implementation details that most developers wouldn’t think matter legally. Do you provide escrow? Dispute resolution? Search functionality that categorises illegal goods? Each feature that makes your platform more useful might also increase your legal exposure.
Payment processors and cryptocurrency exchanges live in constant legal jeopardy. They’re required to implement Know Your Customer (KYC) and Anti-Money Laundering (AML) controls, but the standards keep shifting. What was acceptable compliance three years ago might be criminal negligence today. And if you’re processing payments for a platform that turns out to be facilitating crime, you can be charged as a co-conspirator even if you never looked at what was being sold.
Technical Design Decisions with Legal Consequences
Here’s something they don’t teach you in computer science courses: every architectural decision you make has potential legal ramifications that might not surface for years.
Content moderation is the obvious one. If you build moderation capabilities into your platform, the law will expect you to use them. If you have the technical ability to remove illegal content and you choose not to, that looks like wilful blindness or even active facilitation. But if you don’t build moderation capabilities at all, prosecutors will argue you deliberately designed the platform to evade responsibility.
User verification creates a similar trap. Requiring real names and identity verification makes your platform less attractive to criminals, but it also betrays users in authoritarian regimes who have legitimate reasons for anonymity. Skipping verification protects privacy but makes it trivial for criminals to operate freely. There’s no obviously correct answer, and the legal implications shift depending on what your platform is actually used for.
Data retention policies matter more than most developers realise. Keep logs of user activity and you create evidence that can be subpoenaed. Don’t keep logs and you’ll be accused of deliberately destroying evidence. The European Union’s data retention regulations push in one direction, whilst privacy advocates and cryptographers push in the other, and you’re stuck in the middle trying to write a logging system that won’t land you in prison.
Even your terms of service carry legal weight you might not anticipate. If you prohibit illegal activity but don’t enforce the policy, that’s evidence you didn’t actually care about preventing crime. If you don’t prohibit it at all, that suggests you were comfortable with criminal use. And if you do enforce it inconsistently, prosecutors will paint you as selectively allowing favoured criminals whilst banning others.
Red Flags That Trigger Criminal Liability
Certain patterns almost guarantee you’ll attract prosecution if your platform facilitates any significant criminal activity. Actual knowledge is the brightest red flag. If users are directly telling you they’re selling drugs or stolen data, or if your own investigation reveals widespread illegal use, you can’t unsee it. Continuing to operate the platform at that point is legally indefensible.
Revenue models that depend on transaction volume create powerful evidence of intent. If you take a percentage of every sale, you’re financially incentivised for criminal transactions to succeed. Prosecutors love this because it shows you profited from crime directly, not incidentally. It transforms you from platform operator to business partner.
Active resistance to law enforcement cooperation is catastrophic. You might have principled objections to surveillance or legitimate concerns about user privacy, but if you architect your system specifically to thwart legal investigations or refuse valid warrants, you’re painting a target on yourself. The law distinguishes between protecting privacy and obstructing justice, though the line isn’t always clear.
Marketing matters more than developers typically think. If your promotional materials emphasise that your platform can’t be traced, that law enforcement can’t access it, or that it’s perfect for buying things you couldn’t get elsewhere, you’re providing evidence of your intent. Silk Road’s marketing celebrated its lawlessness. That wasn’t a side effect of the platform, it was the value proposition.
What Criminal Lawyers Say Developers Must Know
This is where developers really need input from criminal defence lawyers, because the technical and legal frameworks operate on completely different logic. Criminal defence specialists, like those at firms such as Podmore Legal in Perth, frequently encounter professionals who genuinely believed their technical safeguards would protect them legally. A criminal defence solicitor will tell you that the “ostrich defence” fails spectacularly in court. Claiming you didn’t know what was happening on your platform doesn’t work when the evidence shows you should have known or deliberately avoided knowing.
Corporate criminal liability is real and growing. It’s not enough to say the company is responsible but you personally aren’t. In the UK, the Corporate Manslaughter and Corporate Homicide Act 2007 and various fraud statutes allow prosecution of both companies and individual directors or senior managers. If you’re the CTO or founder, you can be personally liable for corporate crimes, particularly if you were involved in the decisions that facilitated them.
The international dimension adds another layer of risk. You might be operating legally in one jurisdiction whilst violating laws in another, and extradition treaties mean you can be hauled before courts thousands of miles away. Alexandre Cazes was arrested in Thailand at the request of the United States. Ross Ulbricht was tried in New York for a website that served users globally. Your physical location doesn’t protect you if you’re facilitating crimes in countries with robust extradition agreements.
Criminal lawyers will also tell you that once you’re under investigation, your technical cleverness works against you. Prosecutors will use your sophisticated implementation of anonymity features and anti-forensics techniques as evidence that you knew exactly what you were doing and took deliberate steps to evade detection.
Building Responsibly: A Framework for Developers
So what’s a developer to do? You can’t simply refuse to build anything that might be misused, because that’s essentially all software. But you can make informed decisions that balance innovation with legal risk.
Legal review should happen at the design stage, not after launch. If you’re building anything involving marketplaces, payments, anonymity, or user-generated content, have a criminal lawyer review your architecture before you write a single line of production code. This feels expensive and bureaucratic, but it’s vastly cheaper than defending yourself in court later.
Compliance infrastructure needs to be part of your minimum viable product, not something you add later. Build content moderation tools from day one, even if you don’t use them aggresively initially. Implement logging that captures enough information to respond to valid legal requests without surveiling every user action. Create terms of service that prohibit criminal activity and enforce them consistently.
Know when to engage counsel, and that time is earlier than you think. If you’re seeing patterns that suggest criminal use, don’t investigate on your own. Talk to a lawyer first. If you receive a law enforcement request, don’t respond without legal advice. If your revenue is growing suspiciously fast or you’re attracting users from jurisdictions known for cybercrime, those are signals to get professional guidance.
Documentation protects you, but only if it’s honest. Keep records of your compliance efforts, moderation decisions, and responses to illegal content. But never, ever document that you knowingly allowed illegal activity to continue. Lawyers call that “creating evidence,” and it’s a disaster. Be honest in internal communications about problems you’re seeing and steps you’re taking to address them.
The Path Forward
We’re entering an era where privacy-preserving technology is both more necessary and more legally precarious than ever before. Authoritarian governments are expanding surveillance, corporations are monetising every scrap of user data, and ordinary people are rightfully demanding tools that protect their digital lives. Developers have a responsibility to build those tools.
But we also have a responsibility to understand the legal environment we’re operating in. Building technology isn’t a morally neutral act when you know how it will be used. You can’t hide behind the code and claim you’re merely providing infrastructure when that infrastructure enables serious harm.
The future belongs to developers who can navigate this tension, who can build powerful privacy tools whilst implementing sensible safeguards against abuse. That requires understanding not only how criminal law works but why it works that way. It means engaging with lawyers early and often, even when it slows down development. It means making hard choices about features that might be technically brilliant but legally catastrophic.
Your code has power, and with that power comes consequences you need to understand before you push to production. Ross Ulbricht learned that lesson too late, and he’ll spend the rest of his life in prison because of it. You don’t have to make the same mistake.
