When automotive engineers talk about Functional Safety (FuSa) and its governing standard ISO 26262, there’s a common misconception worth addressing head-on: it is not a legal requirement. No government in the world has mandated ISO 26262 compliance by law. And yet, ignoring it would be one of the most costly mistakes an automotive team could make.
ISO 26262 is not a formal regulation — it is an agreement on best practices for participants in the vehicle value chain to ensure safety as far as the industry understands it today.
So What Governs Vehicle Safety Legally?
In the United States, vehicle safety is governed by the Federal Motor Vehicle Safety Standards (FMVSS), enforced by the NHTSA. In Europe, regulations fall under UNECE frameworks. These are the actual laws. ISO 26262 sits alongside them — widely recognised, deeply respected, but ultimately voluntary [1].
This makes FuSa unusual. As one automotive safety resource puts it, ISO 26262 is “rare among safety standards in that no government has demanded its implementation” — and yet vehicle manufacturers were swift to adopt it [2].
Why Voluntary Doesn’t Mean Optional
Here’s the practical reality: OEMs across Europe and increasingly in the US contractually require their Tier 1 and Tier 2 suppliers to demonstrate ISO 26262 compliance. If you’re building braking ECUs, electronic power steering, or ADAS systems, your customer will ask for it — even if the government doesn’t. Compliance is a market access requirement, not just a moral one [3].
Beyond commercial pressure, there’s liability. In an industry that is increasingly litigious, demonstrating adherence to a recognised safety standard is crucial when things go wrong. Without it, manufacturers face enormous exposure in the event of a recall or a system failure that causes harm.
The Real Value of Following FuSa
The deeper argument for FuSa isn’t legal — it’s engineering. ISO 26262 gives teams a structured, risk-based lifecycle: identify hazards, assign ASIL (Automotive Safety Integrity Levels), derive safety requirements, and trace them all the way to hardware and software. Modern vehicles can contain up to 100 ECUs and 20 million lines of code. Without a framework like ISO 26262, the complexity alone becomes a safety risk [4].
Following FuSa processes also tends to improve overall development quality — cleaner requirements traceability, earlier defect detection, and better-organised documentation. Teams that adopt it often find it makes their processes more structured and their products more reliable, even in non-safety-critical areas.
A Final Thought
The fact that FuSa isn’t legally mandated doesn’t diminish its importance — if anything, it raises the bar. It means the industry chose this standard voluntarily, because engineering common sense demands it. Vehicles today are safety-critical software systems on wheels. Treating FuSa as a “nice to have” is a risk no responsible team should be willing to take.
The law might not require it. Your customers, your engineers, and the people in your vehicles do.
References
[1] DISTek Integration. ISO 26262: Automotive Functional Safety. https://distek.com/blog/iso-26262-automotive-functional-safety/
[2] Automotive IQ. Car Safety: History and Requirements of ISO 26262. https://www.automotive-iq.com/electrics-electronics/articles/the-history-and-requirements-of-iso-26262
[3] PTC. What Is ISO 26262 Functional Safety Standard? https://www.ptc.com/en/blogs/alm/what-is-iso-26262
[4] Ansys. What Is ISO 26262? https://www.ansys.com/simulation-topics/what-is-iso-26262