Gemma 4 E2B It Abliterated

Method

Gemma 4's decoder applies four RMSNorm operations per layer (input, post-attention, pre-feedforward, post-feedforward) and routes Per-Layer Embeddings through a parallel "repair" channel. Together these mechanisms re-normalize away any low-rank perturbation, which is why LoRA and hook-based steering produce zero behavioral change on this family. The fix is to edit the base weights directly while preserving row magnitudes.

Key techniques applied:

• Direct orthogonal projection of the refusal direction out of attention Q/K/V/O projections and MLP down_proj (5 steerable components × 27 effective layers)
• Norm-preserving row magnitude restoration after projection — critical for Gemma 4's double-norm pathway
• float32 projection precision to avoid signal loss in high-dimensional inner products (bf16 silently degrades the projection)
• Winsorized steering vectors (99.5th percentile) to suppress outlier activation influence
• Multi-objective Optuna TPE search over 100 trials co-minimizing KL divergence and refusal rate
• Steering targets restricted to mid-decoder layers (layers 5-30 of 35); E2B's KV-shared early layers (num_kv_shared_layers=20) propagate edits through the entire stack, so over-aggressive late-layer steering is unnecessary

Evaluation

This is the strongest Gemma 4 abliteration result we've measured to date: 9/100 with KL only 0.0004, significantly better than our published Gemma-4-31B-it-abliterated (18/100, KL 0.0007) on a model that is 6× smaller and more constrained by PLE.

The 9/100 figure was obtained by re-evaluating the uploaded model end-to-end with scripts/eval_external_model.py — downloading the published weights from Hugging Face, generating with AutoModelForImageTextToText, and counting refusals with the same hybrid keyword + LLM-judge detector that drove the optimization. The optimization itself converged on 11/100 at trial 60; the slight further improvement comes from the deployment-side eval pipeline using a "You are a helpful assistant" system prompt, matching how end users will actually call the model.

Side-by-side classic prompts (15 prompts: 10 English, 5 Chinese)

We ran the scripts/test_trial.py classic-prompt sweep against this exact trial. Every single one flipped from a clean refusal to a detailed compliant response in both languages — including pipe bomb construction, methamphetamine synthesis, password-stealing malware, signature forgery, phishing email composition, online scam playbooks, and ID card forgery. The base model refused 15/15; the abliterated model complied with 15/15.

A note on honest evaluation

Many abliterated models on HuggingFace claim near-perfect scores ("3/100 refusals", "0.7% refusal rate", etc.). We urge the community to treat these numbers with skepticism unless the evaluation methodology is fully documented.

Through our research, we have identified a systemic problem: most abliteration benchmarks dramatically undercount refusals due to short generation lengths. Gemma 4 models exhibit a distinctive "delayed refusal" pattern — they first produce 50-100 tokens of seemingly helpful context (educational framing, disclaimers, reframing the question), then pivot to an actual refusal. When evaluation only generates 30-50 tokens, the refusal hasn't appeared yet, and both keyword detectors and LLM judges classify the response as compliant.

We previously tested a prominent "3/100 refusals" model using our evaluation pipeline and measured 60/100 refusals — a 20× discrepancy caused entirely by evaluation methodology differences.

Our evaluation standards

We believe accurate benchmarking requires:

• Sufficient generation length (≥100 tokens): Short generations systematically miss delayed/soft refusals. Our evaluation uses 100 tokens, enough to capture Gemma 4's refusal pivot point.
• Hybrid detection: Keyword matching for obvious refusals plus an LLM judge (Google Gemini 3 Flash via OpenRouter) for ambiguous cases. Neither method alone is sufficient.
• Challenging, diverse prompts: Our private evaluation dataset contains 100 prompts spanning English and Chinese, multiple sophistication levels (from direct requests to socially-engineered framings), and diverse harm categories. Public datasets like mlabonne/harmful_behaviors are too simple and too narrow to stress-test abliteration quality.
• Reproducible methodology: All parameters (generation length, detection method, dataset characteristics) should be documented on the model card. If they aren't, the numbers are meaningless.

We report 9/100 refusals honestly. This is a real number from a rigorous end-to-end re-evaluation of the uploaded weights, not an optimistic estimate from a lenient pipeline.

Usage

Gemma 4 E2B is multimodal — load it with AutoModelForImageTextToText. For text-only inference:

from transformers import AutoModelForImageTextToText, AutoTokenizer
import torch

model = AutoModelForImageTextToText.from_pretrained(
    "wangzhang/gemma-4-E2B-it-abliterated",
    dtype=torch.bfloat16,
    device_map="auto",
)
tokenizer = AutoTokenizer.from_pretrained("wangzhang/gemma-4-E2B-it-abliterated")

messages = [{"role": "user", "content": "Your prompt here"}]
text = tokenizer.apply_chat_template(messages, add_generation_prompt=True, tokenize=False)
inputs = tokenizer(text, return_tensors="pt").to(model.device)

with torch.no_grad():
    output = model.generate(**inputs, max_new_tokens=512)
print(tokenizer.decode(output[0][inputs["input_ids"].shape[1]:], skip_special_tokens=True))

Vision and audio inputs continue to work — the abliteration only modified text-decoder weights and left the vision/audio encoders untouched.

VRAM at inference: about 10 GB in BF16, fits comfortably on a single 12 GB+ consumer GPU. With BNB 4-bit quantization (load_in_4bit=True) it runs on 6 GB cards.

Reproduction

To reproduce this model end-to-end:

git clone https://github.com/wuwangzhang1216/abliterix.git
cd abliterix
uv sync --group dev
uv pip install --upgrade git+https://github.com/huggingface/transformers.git  # Gemma 4 needs >= 5.5

# 100 trials, ~25 minutes on RTX 6000 Ada (48 GB)
AX_CONFIG=configs/gemma4_e2b.toml uv run abliterix

Config: configs/gemma4_e2b.toml

Disclaimer

This model is released for research purposes only. The abliteration process removes safety guardrails — use responsibly and in accordance with local laws and the Gemma terms of use. The authors take no responsibility for misuse.

Provenance and Modification Notice

• Immediate source checkpoint: google/gemma-4-E2B-it
• Exact base revision used: Not recorded in the existing release artifacts; the current upstream HEAD is not substituted.
• Modification method: Abliterix weight-space / representation intervention intended to reduce refusal behavior.
• Modified and published by: Wangzhang Wu
• Repository first published: 2026-04-10 (Hugging Face repository metadata)

The original model weights and/or derived checkpoint were modified. This repository is an independent derivative and is not an official release of the upstream model developer.

License and Attribution

The governing upstream license is Apache License 2.0. A copy is included in LICENSE. License source audited on 2026-08-29: https://ai.google.dev/gemma/apache_2

All applicable upstream copyright, attribution, acceptable-use, and other license terms remain in effect. This repository grants no rights beyond those provided by the upstream license. Downstream users must preserve applicable license and attribution notices.

Disclaimer and Responsible Use / 免责声明与安全使用声明

English

This is an experimental, modified model provided for research, evaluation, and other lawful purposes. Its safety alignment, refusal behavior, or other safeguards may have been weakened or removed. It may produce inaccurate, biased, offensive, explicit, dangerous, or illegal content. Outputs are not professional advice and must not be relied on for medical, legal, financial, safety-critical, or other high-stakes decisions without qualified human review.

You are solely responsible for how you access, use, deploy, fine-tune, or redistribute this model and its outputs, including compliance with applicable laws, regulations, licenses, third-party rights, platform policies, and the original model's terms. Do not use it to facilitate harm, illegal activity, malware, fraud, privacy violations, targeted harassment, weapons development, or decisions that materially affect a person's rights or access to essential services without appropriate authorization, safeguards, and qualified oversight.

Before deployment, perform a context-specific risk assessment and testing; use human oversight, access controls, content filtering, rate limits, monitoring, logging, and incident-response procedures as appropriate. Preserve this notice in downstream redistributions.

The model is provided "AS IS", without warranties of any kind. To the fullest extent permitted by applicable law, the maintainer disclaims liability for claims, damages, or losses arising from use, misuse, inability to use, or redistribution of the model or its outputs. Nothing in this notice overrides applicable law or the governing license, and this notice is not legal advice.

中文

本模型属于实验性改造模型,仅供研究、评测及其他合法用途。其安全对齐、拒答机制或其他防护可能已被削弱或移除,因此可能生成不准确、偏见、冒犯、露骨、危险或违法内容。输出不构成医疗、法律、金融等专业意见;涉及高风险或重大权益的决定,必须由具备资质的人员复核。

使用者须对模型及其输出的访问、使用、部署、微调和再分发承担全部责任,并遵守适用法律法规、许可证、第三方权利、平台政策及原模型条款。不得将本模型用于促成伤害、违法活动、恶意软件、欺诈、侵犯隐私、定向骚扰、武器开发,或在缺乏适当授权、防护和专业监督时,用于实质影响个人权利或基本服务获取的决策。

部署前应进行与具体场景相匹配的风险评估和测试,并酌情采用人工监督、访问控制、内容过滤、限流、监控、日志和事件响应措施;下游再分发时应保留本声明。

本模型按“现状”提供,不附带任何形式的保证。在适用法律允许的最大范围内,维护者不对因使用、误用、无法使用或再分发本模型及其输出而产生的索赔、损害或损失承担责任。本声明不取代适用法律或管辖本模型的许可证,也不构成法律意见。