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Custom GPTs for law firms

An AI assistant that knows your firm.

A generic chatbot knows the internet. It does not know your precedents, your processes or your voice. We build custom GPTs trained on your firm’s own knowledge, so your people get answers grounded in how your firm actually works, used safely within professional conduct rules.

What this is really about

Your people are already using AI. On the wrong tools.

The question is no longer whether your firm uses AI. Your lawyers already do, quietly, on public tools that know nothing about your firm and remember nothing safely. The real question is whether that use is grounded in your knowledge and governed by your rules, or happening in the shadows with all the risk that implies.

A generic assistant is confident and often wrong. It does not know your precedents. It does not follow your processes. It does not sound like your firm. And it gives every answer with the same certainty, whether it is right or invented. In a profession where accuracy and confidentiality are not optional, that is not a small problem.

A custom GPT is different. It is trained on your firm’s own knowledge, precedents, brand voice and processes. It answers from what your firm actually knows, within boundaries you set, so your people move faster without stepping outside professional conduct rules.

Illustrative scenario

Consider a mid-sized commercial firm where a junior lawyer, under deadline, pastes a client scenario into a public chatbot and asks it to draft a clause. The tool returns polished, confident wording, and cites a case that does not exist. No one trained it on the firm’s precedents, and no one told it what it must never do with client information. A custom GPT built on the firm’s own precedent bank, with clear guardrails, would have drafted from vetted material, flagged what needed a partner’s eyes, and kept the confidential details inside the firm.

Mark Nelson
BPC Lawyers
“Our experience with Practice Proof has been consistently impressive. Dan and his team are responsible, personable and genuinely trustworthy.”
Why a generic chatbot is not enough

Three reasons off-the-shelf AI fails law firms.

The tools everyone uses were built for everyone. A firm bound by duties of accuracy and confidentiality needs something built for how it actually works.

01

It does not know your firm

A public model answers from the open internet, not from your precedents, your matters or your way of doing things. Ask it something specific to your practice and it guesses, plausibly and generically, when what you needed was your firm’s own answer. A custom GPT is grounded in the knowledge you choose to give it.

02

It has no guardrails you control

Generic tools give confident answers with no sense of what your firm must never do, and offer little assurance about where confidential information goes. Used unsupervised, that is a conduct and confidentiality risk. A custom GPT is built with explicit boundaries, so it knows what to answer, what to escalate and what to refuse.

03

It sounds like everyone else

Off-the-shelf AI writes in a flat, recognisable voice that is not yours. Client-facing work drafted that way erodes the brand you spent years building. A custom GPT is trained on your firm’s voice and templates, so what it produces reads like your firm, not like a machine.

How we do it

We build it on your knowledge, inside your rules.

We start with a real job to be done, ground the assistant in your own material, set the guardrails, and train your people, so it is useful from day one and safe by design.

Step 1

Find the right job

We identify where an assistant genuinely helps, drafting, research triage, intake, first-line client questions, and start where the value is clear and the risk is manageable.

Step 2

Train it on your firm

We ground the GPT in your precedents, templates, processes and brand voice, so its answers come from what your firm knows rather than the open internet.

Step 3

Set the guardrails

We build in the boundaries your conduct obligations demand, what it must never do with client information, when it must escalate to a human, and how it handles what it does not know.

Step 4

Roll out and refine

We train your team, put it to work on real matters, and keep tuning it as your precedents and processes evolve, so it gets more useful over time, not less.

The cost of leaving it

Doing nothing is not the safe option.

Many firms treat AI as something to wait out, as though inaction were the cautious choice. It is not. Your people are already using these tools; the only question is whether that use is grounded and governed, or ungoverned and invisible. Every month without a firm-approved way to work with AI is a month of shadow use you cannot see and cannot control.

Meanwhile, the firms that build this well compound the advantage. A custom GPT trained on your knowledge gets sharper as your precedents grow. Your people get faster at the work only your firm can do. That capability is not bought overnight, which is precisely why starting now matters. A short session shows you where an assistant would help most, and where the guardrails need to be, with no obligation beyond the conversation.

What you are probably thinking

The objections we hear most, answered plainly.

Is this safe with client confidentiality?

That is the first thing we design for, not an afterthought. We build the assistant with explicit boundaries on what it does with client information and where that information can go, so it works within your professional conduct obligations rather than around them.

Will it hallucinate and get things wrong?

Any model can be confidently wrong, which is exactly why we ground it in your vetted material and design it to flag uncertainty and escalate to a human rather than invent. It is built to assist your lawyers, never to replace their judgement.

Isn’t this just the same as ChatGPT?

The underlying technology may be similar; the difference is everything around it. A custom GPT knows your firm, follows your rules and speaks in your voice. A public chatbot knows none of that and answers everyone the same way.

In their words

“Practice Proof have delivered comprehensive marketing tailored to our firm for over 10 years, strategy, website, SEO, Google Ads, content, social, email, podcasts and video, all done exceptionally well and on time.”

Mark Nelson · Partner, BPC Lawyers
A logical next step

Where firms often go from here.

The work compounds when channels connect. These pair naturally with what you just read.

The first step is diagnostic, not a commitment

Find out where AI would actually help your firm.

Start with a short working session. We will map where an assistant would save your people real time, where the guardrails need to be for your conduct obligations, and what a first custom GPT for your firm could safely do.

Book a consultation →
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