Anthropic released Claude 4 on May 22, 2025, and the big story here is not just that a new model arrived. The big story is how the company built it. Claude 4 runs on a technique called “constitutional AI,” and that method—more than the coding upgrades or the new agentic abilities—is what makes this release worth close attention.
Constitutional AI is Anthropic’s signature approach. It trains models to follow a set of written principles, a kind of rulebook written into the model’s learning process. The idea is to align the AI with ethical and legal standards from the ground up, not as an afterthought or a patch. Other companies bolt on safety filters after training. Anthropic builds the rules into the training itself. That distinction has defined the Claude series since its debut in March 2023, and it sets Claude apart in a field where most labs race for raw capability first and worry about consequences later.
That commitment comes with costs. The report notes that Claude’s use by US federal agencies is being phased out due to contractual disagreements. Anthropic lost government business rather than bend on its principles. That is a concrete price, not a hypothetical one. The company chose its method over a major customer. That tells you something about how seriously they take constitutional AI.
Claude 4 arrives in two models at launch: Opus 4 and Sonnet 4. The Claude series typically ships in three sizes—Haiku, Sonnet, and Opus, from least to most capable. This time the top two lead the release. The tiered structure itself is strategic. It lets Anthropic serve users who need basic chatbot functions and users who need the most powerful coding assistant available, all from the same model family. Flexibility and scalability, as the report puts it.
The enhanced coding capabilities are the headline feature. Claude 4 can handle more complex programming tasks and work in an “agentic” mode—meaning it can take multi-step actions on its own, not just answer one question at a time. That is a leap from earlier versions. For software developers, this changes what an AI assistant can do. It moves from a tool that writes snippets to one that can manage larger pieces of a project.
But the coding upgrades are built on top of constitutional AI. The model’s ability to write better code is not separate from its ability to follow rules. The training method that keeps Claude legally and ethically aligned is the same training method that makes it more capable. Anthropic has argued that alignment and capability are not in tension. Claude 4 is the strongest test of that argument so far.
The company was founded with a specific vision for AI’s future. It has not compromised on that vision. The release of Claude 4, with Opus 4 and Sonnet 4 leading the way, is the most visible result of that refusal to compromise. The government contracts are gone. The model is here.
