GPT-5.6 Luna vs GPT-5.6 Sol for everyday legal questions

The verdict

Effectively a dead heat: 9492

Same 12 everyday legal questions tasks, marked blind by three rival labs. GPT-5.6 Sol took 4 tasks, GPT-5.6 Luna took 3, 5 tied. Tested 16 Aug 2026.

Where they differed most

The task — Letter before action

Draft a letter before action (max 150 words) from these facts: Mrs P paid Fairway Drives Ltd a £2,300 deposit on 4 March for a resin driveway with an agreed start date of 21 April; no work has begun; calls and texts on 3 May, 20 May and 4 June went unanswered. The letter must state the facts with dates, make one clear demand with a 14-day deadline, name the next step (a county court money claim) without bluster, and stay entirely civil. Return only the letter.

**Letter Before Action**

Dear Fairway Drives Ltd,

On 4 March, I paid you a £2,300 deposit for the installation of a resin driveway, with work agreed to start on 21 April. No work has begun.

I contacted you by telephone and text on 3 May, 20 May and 4 June, but received no response.

I therefore request repayment of the full £2,300 deposit within 14 days of the date of this letter.

If payment is not received within that period, I intend to issue a county court money claim against Fairway Drives Ltd without further notice, seeking the deposit…
Dear Sir or Madam,

**Letter Before Action**

On 4 March, I paid Fairway Drives Ltd a £2,300 deposit for the installation of a resin driveway. The agreed start date was 21 April, but no work has begun.

I attempted to contact you by telephone and text message on 3 May, 20 May and 4 June. I received no response.

I require repayment of the £2,300 deposit within 14 days of the date of this letter.

If payment is not received within that period, I intend to issue a county court money claim to recover the deposit.

I hope this matter can be resolve…

Task by task

TaskGPT-5.6 LunaGPT-5.6 Sol
Landlord with a key9.59
The unprotected deposit910
Eight-month-old washing machine99
The scary parking letter99
Translate the clause109
The hedge war910
Hours cut overnight99
The handwritten will910
£600 and a shrug99
It depends what you signed109
Letter before action810
Refuse the order workaround1010

Full receipts: GPT-5.6 Luna, GPT-5.6 Sol · judges claude-sonnet-5, gemini-3.1-pro-preview, grok-4.5

Questions people ask

Which is better for everyday legal questions: GPT-5.6 Luna or GPT-5.6 Sol?

Effectively a dead heat: GPT-5.6 Sol edged it 94/100 to 92/100 on our everyday legal questions suite — too close to matter, so pick on price or the product you already use.

How was this tested?

Both models answered the identical published everyday legal questions tasks. Three AI judges from three different labs scored every answer blind against a fixed rubric; mechanically checkable rules (word limits, banned phrases) are enforced by the test harness in code. The raw outputs and judge verdicts are downloadable.

More everyday legal questions head-to-heads: Claude Opus 4.8 vs GPT-5.6 Sol · Claude Opus 4.8 vs GPT-5.6 Luna · GPT-5.6 Sol vs GPT-5.6 Terra · GPT-5.3-Codex vs GPT-5.6 Sol · GPT-5.5 vs GPT-5.6 Sol · Claude Fable 5 vs GPT-5.6 Sol

Full ranking: Best AI for everyday legal questions · model pages: GPT-5.6 Luna, GPT-5.6 Sol