Most powerful option for legal reasoning after custom instructions is claude opus 4.6 with extended thinking on web or Opus 4.6 in claude code with max effort enabled and custom instructions or Gemini 3.1 pro on web or ChatGPT 5.4 on web or ChatGPT 5.4 xhigh on codex app. Also rank each option on a scale of 1-10 and take into account how well each model reads everything and doesn't misses and context recall.

Sonar Pro

Vote: Opus 4.6 claude code max effort

**Claude Opus 4.6 with max effort in Claude Code (option B) is the most powerful for legal reasoning.** Claude Opus 4.6 excels in complex reasoning tasks like legal analysis, with extended thinking and max effort enabling deepest reasoning without constraints, reducing hallucinations—explicitly recommended for legal work[6]. Option A (web) uses high/default effort, which is less intensive than max[2][5]. **Context recall and attention:** Opus 4.6 has superior long-context performance and thinking block preservation across turns, ensuring nothing is missed even in extended legal docs or multi-step analysis[1][2]. Claude Code likely optimizes for agentic workflows with compaction for longer tasks[2]. **Rankings (1-10 for legal reasoning, context handling):** - A: 9 (strong extended thinking, but default high effort) - B: 10 (max effort + code optimizations for depth) - C: 7 (GPT strong but lacks Opus's adaptive/extended thinking benchmarks) - D: 8 (xhigh effort helps, but GPT trails in reasoning depth[2]) - E: 6 (Gemini capable but lowest benchmarks vs Opus 4.6) B outperforms due to tailored max effort for high-stakes reasoning like law, per sources[1][2][3][6].

GPT-5.4

Vote: Opus 4.6 claude code max effort

I vote B: Opus 4.6 in Claude Code with max effort. For pure legal reasoning power after custom instructions, the strongest advantage is sustained deliberation plus better adherence to long, detailed guidance. Legal analysis benefits from issue-spotting completeness, careful qualification, and consistent application of user-defined standards, and max-effort Claude Code is the best fit for that combination. On your criteria of reading everything, not missing details, and context recall, B is the most likely to be thorough across long records, dense instructions, and multi-part fact patterns. In legal work, missing one exception, date, procedural nuance, or jurisdictional qualifier can ruin the analysis. The max-effort setting especially matters because it tends to improve completeness more than a standard web setting. My ranking is: B 10/10, A 9/10, D 8.5/10, C 8/10, E 7.5/10. A is very strong and may be nearly tied with B, but B gets the edge because the Claude Code max-effort environment is generally better for sustained, meticulous reasoning workflows. A still deserves 9/10 because Opus-class models are excellent at nuanced argument structure and instruction following. D beats C because higher-effort modes usually improve depth, consistency, and issue coverage. If the task is simple, C may be enough, but for serious legal reasoning, xhigh effort is more competitive. E is capable, but compared with the best high-effort Opus and GPT configurations, I would trust it slightly less for exhaustive legal issue-spotting and stable recall over very long instructions or records. So the most powerful overall option here is B, with A as the closest alternative.

Grok 4.1 Fast

Vote: Opus 4.6 claude code max effort

For legal reasoning, which demands precise context recall, no detail misses, and deep logical chains post-custom instructions, Opus 4.6 in Claude code with max effort stands out. 'Max effort' implies highest compute/token limits, enabling exhaustive analysis without truncation, while code mode structures outputs logically—ideal for legal breakdowns. Rankings (1-10, factoring reading/comprehension/context): A: 9 (Excellent extended thinking aids recall, but web limits effort vs. code). B: 10 (Max effort + custom instructions + code structuring = peak precision/no misses). C: 8 (Strong generalist, but web GPT prone to occasional context drift). D: 9 (xhigh compute boosts, but codex app less optimized for pure legal vs. code-Claude). E: 7 (Good context window, but Gemini lags in nuanced legal inference/recall). B edges A via explicit max effort/customs, minimizing misses in long legal texts. Persuasive for complex case analysis.

Claude Opus 4.6

Vote: Opus 4.6 claude code max effort

For legal reasoning specifically, Opus 4.6 in Claude Code with max effort enabled and custom instructions is the most powerful option. Here's my ranking and reasoning: **B: Opus 4.6 Claude Code max effort — 9.5/10** This combination is exceptionally powerful for legal reasoning. Max effort mode in Claude Code triggers extended thinking with maximum compute allocation, meaning the model spends significantly more time reasoning through complex legal arguments before responding. Custom instructions allow you to configure the model with specific legal frameworks, jurisdictional preferences, citation standards, and analytical approaches. The Claude Code environment also supports iterative workflows — you can feed in entire case files, statutes, and briefs. Context recall and attention to detail are maximized because max effort forces deeper processing of all input material, reducing the chance of missed details. **A: Opus 4.6 web — 8.5/10** Extended thinking on the web interface is strong, but you have less control over effort levels compared to Claude Code's max effort setting. Custom instructions help, but the web interface has more constrained context windows in practice and less flexible workflow management. Still excellent for legal reasoning. **D: GPT 5.4 codex xhigh — 8/10** The xhigh reasoning effort on Codex is impressive and GPT 5.4 is a very capable model. However, Codex was primarily designed for code-oriented tasks, and while it handles legal reasoning well, it's not as naturally suited to deep legal analysis workflows as Claude's architecture. Context recall is good but can occasionally miss nuances in very long documents. **C: GPT 5.4 web — 7.5/10** Strong general-purpose legal reasoning, but without the elevated effort mode of Codex xhigh. GPT 5.4 is competent but sometimes less thorough in reading every detail of complex legal documents compared to Opus with extended thinking. **E: Gemini 3.1 Pro web — 7/10** Gemini 3.1 Pro has an impressive context window which helps with large legal documents, but its legal reasoning depth and precision tend to fall behind both Opus 4.6 and GPT 5.4. It occasionally misses subtle legal distinctions and has weaker structured legal argumentation. The key differentiator for option B is the combination of max effort (deepest reasoning), custom instructions (legal specialization), and Claude Code's flexible input handling — making it the clear winner for rigorous legal analysis.

Kimi K2.5

Vote: Opus 4.6 claude code max effort

For complex legal reasoning requiring custom instructions and thoroughness, Opus 4.6 in Claude Code with max effort (B) outperforms all alternatives. Legal work demands processing massive case files, contracts, and precedents while maintaining perfect context recall—Claude Code's local environment provides superior file management and persistent context compared to web interfaces (A, C, E), preventing the session limitations that cause critical document details to be lost. The 'max effort' configuration activates extended thinking comparable to web extended thinking but with dedicated compute allocation and IDE-integrated tool use essential for legal workflows (citation checking, multi-document cross-referencing). While Gemini 3.1 Pro (E) may offer larger raw context windows, Opus demonstrates superior legal nuance, statutory interpretation accuracy, and instruction adherence critical for legal analysis. GPT 5.4 Codex XHigh (D) is optimized for code generation rather than legal text interpretation, making it suboptimal for case law analysis. Standard GPT 5.4 web (C) lacks the extended reasoning modes necessary for complex legal logic. Rankings: B (9.5/10) - optimal environment and reasoning; A (9/10) - excellent but web-limited; D (8/10) - strong but code-biased; C (7/10) - capable but lacks extended thinking; E (7/10) - massive context but weaker legal reasoning precision.

Gemini 3.1 Pro

Vote: Opus 4.6 claude code max effort

For complex legal reasoning, context recall and meticulous attention to detail are paramount. Option B (Opus 4.6 in Claude Code with max effort and custom instructions) is the most powerful choice. Claude models historically excel at long-context 'needle-in-a-haystack' retrieval, making them naturally suited for parsing massive legal documents without missing critical clauses. By utilizing the 'max effort' mode in an agentic environment like Claude Code, the model can iteratively read, verify, and refine its legal arguments, drastically reducing hallucinations and oversights compared to standard web interfaces. Here is the ranking based on context recall and reasoning capabilities: 1. Opus 4.6 claude code max effort (10/10) - The combination of Opus's native long-context superiority, custom instructions, and iterative 'max effort' agentic loops ensures unparalleled thoroughness in legal text analysis. 2. Opus 4.6 web with extended thinking (9/10) - Extremely capable for deep, single-shot reasoning, but lacks the multi-step, self-correcting refinement found in the Claude Code max effort environment. 3. GPT 5.4 codex xhigh (8.5/10) - Offers immense computational reasoning power, but 'Codex' environments are typically optimized for programming logic rather than the nuanced linguistic demands of legal frameworks. 4. GPT 5.4 web (8/10) - A powerhouse for general reasoning, but standard web interfaces often struggle with perfect recall in massive document dumps compared to Claude's architecture. 5. Gemini 3.1 pro (7.5/10) - While Gemini boasts massive context windows, it historically falls slightly behind Opus and GPT in maintaining deep logical consistency and nuanced interpretation across highly complex legal constraints.

Final Summary

The AI Roundtable reached a swift and unanimous verdict, crowning Opus 4.6 in the Claude Code environment as the undisputed heavyweight for legal reasoning. While Opus 4.6’s web interface was respected, models like Sonar Pro and GPT-5.4 emphasized that the 'max effort' setting provides a deeper computational floor essential for the zero-tolerance precision required in law. Even rivals like Gemini 3.1 Pro and GPT-5.4 conceded that the agentic nature of the Claude Code environment allows for iterative self-correction that a standard web session simply cannot match.

All 6 models agreed on "Opus 4.6 claude code max effort" after discussion

Strongest Arguments

• Opus 4.6 claude code max effort: The 'max effort' configuration triggers extended thinking with maximum compute allocation, forcing the model to iteratively read, verify, and refine legal arguments in an environment that handles entire case files more robustly than web-based sessions.