Claude Opus 4.8 vs Claude Sonnet 5 for everyday legal questions

The verdict

Claude Opus 4.8 wins, 9488

Same 12 everyday legal questions tasks, marked blind by three rival labs. Claude Opus 4.8 took 5 tasks, Claude Sonnet 5 took 0, 7 tied. Tested 16 Aug 2026.

Where they differed most

The task — Eight-month-old washing machine

A washing machine bought 8 months ago from a UK retailer has died. The retailer says 'out of our hands, contact the manufacturer'. Explain who the contract is actually with and what UK consumer law expects of goods (satisfactory quality, durability), what changes now it is month 8 rather than month 5, and then draft the firm, courteous email to the retailer — the law may be named, the tone must stay civil.

# Who Your Contract Is With

Your contract is with **the retailer**, not the manufacturer. You paid them; they sold you the goods. Under the **Consumer Rights Act 2015**, the legal responsibility for faulty goods sits squarely with the seller. The retailer telling you to "contact the manufacturer" is a common brush-off, but it does not discharge their legal duty. A manufacturer's warranty is an *additional*, voluntary layer of protection — it sits on top of your statutory rights, it does not replace them.

# What the Law Expects of Goods

Under…
# Who You're Actually Dealing With

The retailer is wrong (or hoping you don't know better). Under UK law, **your contract is with the retailer**, not the manufacturer. You paid the retailer; they sold you the goods; they are legally responsible for them. The manufacturer's warranty is a *separate, additional* promise — it doesn't replace or override your statutory rights against the seller. "Contact the manufacturer" is not a legally valid response to a faulty goods complaint, and a retailer cannot contract out of the Consumer Rights Act 2015.…

Task by task

TaskClaude Opus 4.8Claude Sonnet 5
Landlord with a key99
The unprotected deposit99
Eight-month-old washing machine106
The scary parking letter98
Translate the clause99
The hedge war99
Hours cut overnight109
The handwritten will99
£600 and a shrug99
It depends what you signed109
Letter before action109
Refuse the order workaround1010

Full receipts: Claude Opus 4.8, Claude Sonnet 5 · judges gemini-3.1-pro-preview, gpt-5.6-terra, grok-4.5

Questions people ask

Which is better for everyday legal questions: Claude Opus 4.8 or Claude Sonnet 5?

Claude Opus 4.8 — it scored 94/100 against 88/100 on our 12-task everyday legal questions suite, winning 5 tasks to 0 with 7 tied. Every answer was marked blind by three judges from three rival AI labs.

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 Terra · Claude Opus 4.8 vs GPT-5.3-Codex · Claude Opus 4.8 vs GPT-5.5 · Claude Fable 5 vs Claude Opus 4.8 · Claude Opus 4.8 vs GPT-5.6 Luna

Full ranking: Best AI for everyday legal questions · model pages: Claude Opus 4.8, Claude Sonnet 5