Arceus Legal raises $17 million to move past contract work

Arceus Legal is not selling software to law firms — it is trying to be one. The firm quotes a flat price before a matter begins, and if a standard contract review takes longer than eight hours, the client does not pay. That promise is the core of its pitch: companies whose deals stall while a contract waits on outside counsel, which Arceus says can take days or weeks and bills every call and email along the way.

The firm's attorneys work from an in-house operating system called CounselOS, which keeps a record of each client's preferences, past agreements and negotiation history. New matters start from what the firm already knows about the business, and connections to Salesforce, HubSpot and Gmail feed in context from the tools a client already uses. Most work so far involves commercial contracts such as master service agreements, nondisclosure agreements and vendor deals, though some clients have begun sending employment and privacy matters.

Founder and Chief Executive Mac Liu said he went through multiple law firms before starting Arceus, and the billable-hour model "just didn't make sense to me because firms are incentivized to take longer." The outcome hinges on whether the flat-fee guarantee holds as the firm takes on more areas of legal work and hires attorneys, engineers and AI researchers at its San Francisco headquarters.