AI in a law firm: what each case file really costs

Law firms are adopting artificial intelligence faster than they are changing the way they charge. A legal industry survey published in September 2026 sums it up: only 29% of firms have changed how they price AI-assisted work; 30% keep charging the same and bank the efficiency, and another 30% are still evaluating it.

Behind this lies a more basic problem: to know what AI saves you, you need to know what each case file costs you today. And in most firms that figure does not exist. The bill exists, which is something else.

The cost of a case file is not what you bill

The bill says what you charge. The cost says what it takes to produce it: the hours of every person who touches the file, at their real cost to the firm (salary, social security and a share of overheads), plus external costs such as experts, court fees or travel.

You do not need a complicated system to calculate it. It is enough to split the file into phases and log the hours for each one over a few weeks:

• Intake and documentation: first meeting, collecting and organising papers.
• Analysis: reading the case documentation; in many matters, medical, expert or clinical reports.
• Research: finding the applicable legislation and case law.
• Drafting: claim, appeal, brief or report.
• Follow-up: communications with the client and the other side, deadlines and notifications.
• Hearing or negotiation, where there is one.

That already shows where the time goes. Almost always, the surprise is in analysis and drafting.

Where the cost really falls

AI does not make every phase cheaper in the same way. It shows most in the ones that consist of reading a lot and writing with structure:

• Analysis of extensive documentation. A well-designed system reads the whole file, including the medical reports, and prepares a summary of the relevant facts and where each one is.
• Drafting. From that analysis and the firm's own templates, it produces a first draft that the lawyer reviews and corrects.
• Case law research, citing each judgment so it can be checked.

A real case: at a firm that works with legal and medical information, each analysis document took a lawyer between 2 and 3 hours. With a custom application, which always works with pseudonymised data, those documents are generated in minutes and in more detail, and the lawyer spends their time reviewing them. It has been in production since July 2026 and has generated more than 20 documents (see the case, in Spanish).

Where it does not fall, or falls little: strategy, hearings, negotiation and the client relationship. That is judgement work, and there AI at most prepares material.

An example with round numbers

These figures are not from any real firm; they are there to show the calculation:

• A typical file requires three analysis documents of 2.5 hours each: 7.5 hours.
• If that lawyer's hour costs the firm €45, the analysis costs €337.50.
• With AI, each document becomes a review of about 40 minutes: 2 hours in total, €90.
• The difference, €247.50 per file, is what has to be compared with the cost of the tool.

With 20 files of that type a month, that is almost €5,000 of hours no longer spent reading and typing, which can go to more matters or higher-value work.

What the AI costs

There are two routes, and both make sense depending on the firm:

• A legal copilot by subscription. It searches case law, drafts with general templates and reviews contracts. The published rates of those operating in Spain range from about €79 to €150 per user per month, excluding VAT (September 2026). It is the sensible option for a sole practitioner or for general use.
• A custom application on your own files. It works with your templates, with the way you reason each type of matter and with your data, including health data, with the treatment it requires. It pays off when there is volume of the same type of file and when the value lies in your documentation, not in general case law. At Tecnea, the proof of concept starts at €850, full development ranges from €5,000 to €20,000 and the monthly fee starts at €250 (what each amount includes, in Spanish).

If there is medical data: five requirements

Health data is a special category under the GDPR (Article 9), and case files are also subject to professional secrecy. If you are looking for someone to develop an application to draft documents and search case law with medical data in compliance with the GDPR and the AI Act, ask for these five things in writing:

1. Pseudonymisation before the information reaches the model: names and identifying data replaced, with the key kept only at the firm.
2. Processing on servers in the European Union, with a data processing agreement.
3. No use of the data to train models, neither the provider's own nor third parties'.
4. Mandatory human review of everything produced: a lawyer signs the document.
5. Documentation of the system under the AI Act: what it does, with what data and who supervises it. The risk classification depends on the specific use and should be reviewed case by case.

There is more on professional secrecy in AI and professional secrecy in law firms (in Spanish).

What to do with the savings

The same survey reports that 53% of firms say their clients accept the same fees when AI improves value or outcomes. There are three options, and they are not mutually exclusive: keep the price and gain margin, lower it to gain volume, or move to fixed fees per type of file, which is where efficiency turns directly into profit.

Any of the three needs the same thing: measuring the cost before and after.

If you want to see how we approach it for law firms: AI for law firms · Cases in production (in Spanish)

This article is informational and does not constitute legal advice. Tecnea develops AI applications for law firms and has one in production, so we have a direct commercial interest in the topic. The five requirements work for evaluating any proposal, including ours.

Sources

• Artificial Lawyer, "AI Is Forcing Law Firms To Get Serious About Matter Economics" (28 September 2026), with data from BigHand's 2026 report: artificiallawyer.com
• Regulation (EU) 2016/679 (GDPR), Article 9: eur-lex.europa.eu
• Public rates of the legal copilots operating in Spain, checked on 29 September 2026.