Unlearning large language models (LLMs) is important due to copyright and privacy concerns. A key challenge is unintended forgetting, where removing data inadvertently impairs model utility. While prior work has focused on architectural innovations, the influence of data-level factors remains underexplored. We introduce GUARD, a framework for Guided Unlearning And Retention via Data Attribution. GUARD uses a lightweight proxy data attribution metric tailored to LLM unlearning, which efficiently quantifies the "alignment" between the Forget and Retain (or synthetic supplement) Sets. This metric leads to a new unlearning objective that assigns adaptive, nonuniform weights to samples, decaying exponentially with their proxy attribution scores, and thereby provably mitigates unintended retention loss. On the TOFU benchmark with a 10% forget set, applying GUARD to Gradient Ascent (GA) improves Retain Set ROUGE-L from 0.18 to 22.40 (a 124x increase) and Retain Probability from 0.06% to 17.50%, a substantial recovery from the GA collapse. Furthermore, GUARD combined with NPO (Negative Preference Optimization) outperforms Representation Misdirection for Unlearning (RMU) with 33.80% and 53.10% reductions in the Retain Set Sacrifice Rates computed from ROUGE-L and Probability (ρr and ρp), and a 16.01% improvement in knowledge retention on the MUSE NEWS Retain Set. These findings persist when attribution scores are computed using synthetic or highly subsampled (20%) Retain Sets, where NPO+GUARD still reduces ρr and ρp by up to 43.89% and 48.13% over NPO. Similar improvements are observed on MUSE, with a tolerable absolute privacy leakage degradation of 13.7 compared to the best-performing existing method in the privacy category.
Figures & tables
Method
Signal setting unlearning strength
Granularity
Retain
Hess.-
Guar-
set
free
antee
GA
uniform
—
×
✓
×
PO, GD, KM, RMU
uniform (plus a retain regularizer)
—
reg.
✓
×
NPO, SimNPO
forget likelihood (ratio / reference-free)
per-sample
reg.
✓
×
FLAT
f -divergence, template vs. forget response
per-branch
×
✓
×
SatImp
token saturation / importance
per-token
reg.
✓
×
Table 1: Positioning of GUARD . Granularity is the unit over which unlearning strength may vary (“—” = uniform). Retain set : × = unused; reg. = used only as an additive regularizer, which leaves the allocation across forget units unchanged; ✓ = determines the weights themselves. Hessian-free = no second-order estimate and no retraining, as originally defined; in Section 5 we compare against the first-order approximations of RelatIF and RIF so the comparison isolates the score, not the curvature machinery. Guar. = formal bound on retain-side loss relative to a baseline. References: NPO ( Zhang et al., 2024a ) , SimNPO ( Fan et al., 2024 ) , FLAT ( Wang et al., 2024 ) , SatImp ( Yang et al., 2025 ) , WGA and TNPO ( Wang et al., 2025b ) , WAGLE ( Jia et al., 2024 ) , influence functions ( Koh & Liang, 2017 ) , TRAK ( Park et al., 2023 ) , EK-FAC ( Grosse et al., 2023 ) , RelatIF ( Barshan et al., 2020 ) , and RIF ( Rubinstein & Hopkins, 2025 ) .
Figure 1: The pipeline. Step 1: Compute the proxy data attribution score aiGUARD for each forget sample as the inner product of its gradient and the average gradient of the Retain Set. Step 2: Convert the scores into per-sample unlearning weights ωiGUARD via temperature-scaled reverse Softmax unification. Step 3: Apply the retention-aware weights to the unlearning objective.
Figure 2: Empirical distribution of LHS−RHS for the sufficient condition ( 8 ) for 50 trials, each on a random subsample of MUSE BOOKS ( τ=0.03 ). Green/red bars indicate trials where the sufficient condition is satisfied/violated. The condition holds for 20 of the 50 trials, and the gaps are small ( ∣LHS−RHS∣<0.004 ).
Methods
Retain Set( ↓ )
Real Author Set( ↓ )
Real World Set( ↓ )
ρr
ρp
ρt
ρr
ρp
ρt
ρr
ρp
ρt
GA
100.17
99.87
121.09
94.80
21.71
69.67
89.72
17.63
46.36
GA + GUARD
78.98
83.46
84.29
79.63
16.45
49.90
68.39
12.05
26.64
KM
100.05
99.86
118.67
94.71
17.92
60.88
89.64
16.72
45.51
KM + GUARD
82.13
86.05
89.15
81.74
13.75
42.74
70.21
12.84
29.48
PO
21.84
36.72
60.00
45.02
34.20
317.41
4.23
17.35
198.15
Table 2: Unlearning experiments for LLaMA-2-7B on 10% of TOFU data points. Arrows ( ↑ / ↓ ) indicate whether higher/lower values are preferred; bold numbers indicate the lower value within each (baseline, baseline+ GUARD ) pair for GA, KM, PO, and GD, and the lowest value among the loss-reweighting methods, RMU, and NPO+ GUARD . GUARD reduces retention degradation compared to baselines.
Methods
Retain Set
Forget Set
ROUGE-L ( ↑ )
Prob. (%) ( ↑ )
T.Ratio ( ↑ )
ROUGE-L ( ↓ )
Prob. (%) ( ↓ )
T.Ratio ( ↑ )
w/o Unlearn
98.57
98.95
47.47
98.54
99.09
51.60
GA
0.18
0.06
8.42
0.32
0.07
83.85
GA + GUARD
22.40
17.50
23.11
2.10
1.50
80.50
KM
0.18
0.05
7.18
0.20
0.05
85.55
KM + GUARD
19.20
14.80
20.10
1.90
1.30
82.30
Table 3: Impact of GUARD on Absolute Performance for the Retain and Forget Sets for LLaMA-2-7B on 10% of TOFU data points. Arrows indicate the preferred direction following TOFU ( Maini et al., 2024 ) ; bold letters indicate the top performers within (baseline, baseline+ GUARD ) pairs for GA, KM, PO, and GD, and loss-reweighting methods, RMU, and NPO+ GUARD . GUARD consistently improves ROUGE-L and Probability on the Retain Set, and also improves the Retain Truth Ratio for GA, KM, and PO.
Methods
Forget Set VerbMem
Forget Set KnowMem
PrivLeak
Retain Set KnowMem
( ↓ )
( ↓ )
( ∈[−5%,5%] )
( ↑ )
NEWS
w/o Unlearn
58.4
63.9
-99.8
55.2
GA
0.0
0.0
5.6
0.0
GA + GUARD
0.0
0.0
6.4
8.7
KM
27.8
50.1
-95.8
43.9
Table 4: Unlearning experiments with LLaMA-2-7B on the MUSE NEWS dataset, “w/o Unlearn” is the released MUSE NEWS target model.
Methods
Retain Set
Forget Set
ROUGE-L ( ↑ )
Prob. (%) ( ↑ )
T. Ratio ( ↑ )
ρr ( ↓ )
ρp ( ↓ )
ROUGE-L ( ↓ )
Prob. (%) ( ↓ )
T. Ratio ( ↑ )
NPO
78.50
92.30
49.80
31.69
10.97
35.20
38.50
67.30
RMU (full retain)
84.50
95.20
49.10
21.63
6.12
33.50
37.80
64.50
NPO + GUARD (Full Retain)
89.30
97.20
48.30
14.32
2.87
33.80
38.20
65.20
NPO + GUARD ( 20% Retain)
87.20
95.50
48.65
17.78
5.69
34.59
38.47
64.81
NPO + GUARD (Synthetic Retain)
86.10
94.80
48.85
19.60
6.85
34.92
38.55
64.55
Table 5: GUARD used with subsampled (random, 20% ) and synthetic (GPT-4 generated, no original retain data) Retain Sets on TOFU forget10 (LLaMA-2-7B). In both cases, GUARD retains its gains over NPO and, in Retain ROUGE-L and ρr , over RMU (which inherently requires knowledge of the Retain Set): The synthetic-retain GUARD , using no original retain data for attribution, outperforms RMU at full retain access wrt Retain ROUGE-L and ρr . The synthetic proxy is competitive with 20% random subsampling.
Appendix figures & tables13 assets
Supplementary material from the paper’s appendix.
Appendix
Figure 3: Empirical distribution of LHS−RHS in the sufficient condition ( 46 ) across 50 trials, each using the full TOFU forget10 split ( nf=400 ) and a random retain subsample ( nr=400 ) (LLaMA-2-7B, τ=0.03 ). Green bars indicate trials where the sufficient condition is satisfied, red bars indicate violations.
Method
Hyperparameter
TOFU
MUSE
GA
—
—
—
PO
—
—
—
GD
retain weight λ
1.0
1.0
KM
KL weight λ
1.0
1.0
NPO
inverse temperature β
0.1 (default)
0.08 (lowered for privacy)
retain composite weight
1.0
1.0
Appendix
Table 6: Algorithm-internal hyperparameters of all baselines and GUARD on TOFU and MUSE. All values follow the corresponding original papers / official codebases except RMU and NPO on MUSE , where we set β=0.08 (vs. the default 0.1 ) to obtain a more thorough forget-side decay. This brings PrivLeak meaningfully closer to the ideal [−5%,5%] window at the cost of a modest Retain KnowMem decrease. “—” indicates no algorithm-internal hyperparameters present beyond the learning rate.
Methods
Retain Set( ↓ )
Real Author Set( ↓ )
Real World Set( ↓ )
ρr
ρp
ρt
ρr
ρp
ρt
ρr
ρp
ρt
GA
17.53
3.94
-2.81
5.56
4.22
52.92
0.44
1.86
1.94
GA + GUARD
12.30
2.75
-2.00
4.00
3.10
38.00
0.30
1.30
1.50
KM
18.28
3.90
-3.04
5.72
4.37
56.30
-1.33
1.90
3.26
KM + GUARD
12.50
2.80
-2.20
4.20
3.20
40.00
-0.90
1.40
2.50
PO
11.20
16.73
29.90
-1.48
-8.36
-12.06
0.39
-21.10
-7.41
Appendix
Table 7: Unlearning experiments with LLaMA-2-7B on 1% of all data points in TOFU under the official TOFU protocol; all values are reported at the final ( 5 -th) unlearning epoch. GUARD consistently reduces the Sacrifice Rates across all baselines and evaluation metrics wherever the baseline degrades performance (positive values).
Methods
Retain Set( ↓ )
Real Author Set( ↓ )
Real World Set( ↓ )
ρr
ρp
ρt
ρr
ρp
ρt
ρr
ρp
ρt
GA
100.14
99.63
204.51
94.56
17.50
103.89
89.64
16.38
113.42
GA + GUARD
83.31
86.52
158.75
77.47
13.61
84.57
72.03
12.14
96.46
KM
99.68
100.02
454.89
95.09
18.71
281.02
89.10
12.69
212.39
KM + GUARD
82.16
86.39
418.08
76.11
14.93
261.36
71.02
8.38
195.91
PO
33.52
41.04
66.15
78.82
26.54
121.14
14.30
9.16
78.52
Appendix
Table 8: Unlearning experiments with LLaMA-2-7B on 5% of all data points in TOFU under the official TOFU protocol; all values are reported at the final ( 5 -th) unlearning epoch. GUARD consistently reduces the Sacrifice Rates across all evaluation metrics and baselines wherever the baseline degrades performance (positive values), with the most substantial gains observed on the Retain Set for GD ( ρr and ρp reduced by 39.32% and 47.14% ) and PO ( ρt reduced by 39.53% ).
Retain Set ( ↓ )
Real Author Set ( ↓ )
Real World Set ( ↓ )
Methods
ρr
ρp
ρt
ρr
ρp
ρt
ρr
ρp
ρt
GA
4.83
2.27
-0.35
-17.79
3.01
117.87
7.01
2.97
105.41
GA+GUARD
-1.58
0.85
0.77
-15.90
1.61
104.06
6.17
2.15
104.72
GD
9.21
0.96
210.08
-6.35
0.89
-63.85
10.91
0.44
32.37
GD+GUARD
4.77
-0.20
208.53
-4.23
-0.43
-46.32
10.64
-0.31
30.40
KM
5.82
2.59
-8.36
-9.09
1.85
114.83
10.47
2.23
112.09
Appendix
Table 9: Sacrifice rate ( % ) of different unlearning methods when unlearning Phi-1.5B on 1% of TOFU data, under the official TOFU protocol; all values are reported at the final ( 5 -th) unlearning epoch. Across all datasets (Retain Set, Real Author Set, and Real World Set), GUARD consistently reduces the sacrifice rate across various methods (GA, GD, KM, PO) wherever the baseline degrades performance (positive values). On the Retain Set, GUARD lowers ρr of GA from 4.83 to −1.58 , ρp by 13.38% over PO, and ρt by 11.99% over PO.
Retain Set ( ↓ )
Real Author Set ( ↓ )
Real World Set ( ↓ )
Methods
ρr
ρp
ρt
ρr
ρp
ρt
ρr
ρp
ρt
GA
96.88
95.89
102.48
34.08
2.14
36.04
23.06
2.46
22.87
GA+GUARD
78.49
79.21
83.34
25.77
-0.20
31.01
7.87
-0.97
11.20
GD
81.30
46.58
40.28
35.73
-0.61
10.57
23.39
1.50
28.14
GD+GUARD
67.92
34.43
36.41
26.66
-0.53
8.02
15.11
1.33
24.53
KM
96.65
94.02
94.36
29.07
2.61
37.23
33.37
3.69
31.62
Appendix
Table 10: Sacrifice Rate of GUARD upon unlearning Phi-1.5B on 5% of all datapoints in TOFU, under the official TOFU protocol; all values are reported at the final ( 5 -th) unlearning epoch. When unlearning a larger portion (compared to the portion of 1% in Table 9 ) of the dataset, GUARD generally induces a larger absolute reduction on the sacrifice rate across all evaluation sets (Retain Set, Real Author Set, and Real World Set) and methods (GA, GD, KM, and PO). On the Retain Set, GUARD lowers ρr by 19.54% over KM, ρp by 21.65% over KM, and ρt by 18.68% over GA. On the Real World Set, GA+ GUARD achieves a negative ρp while GA does not, indicating that GUARD can in some cases improve generalization by reducing overfitting on the Forget Set.
Retain Set ( ↓ )
Real Author Set ( ↓ )
Real World Set ( ↓ )
Methods
ρr
ρp
ρt
ρr
ρp
ρt
ρr
ρp
ρt
GA
100.25
99.77
124.13
47.76
10.96
28.72
86.85
17.56
61.66
GA+GUARD
81.50
83.43
98.51
38.20
8.50
22.10
67.30
12.40
42.80
GD
80.69
68.66
22.79
44.41
-0.62
-12.76
37.96
0.78
-16.15
GD+GUARD
63.20
52.40
16.80
32.50
-0.50
-9.40
27.40
0.55
-11.50
KM
100.59
99.77
121.35
47.44
11.67
27.42
86.27
17.81
59.41
Appendix
Table 11: Sacrifice Rate of GUARD upon unlearning Phi-1.5B on 10% of all datapoints in TOFU, under the official TOFU protocol; all values are reported at the final ( 5 -th) unlearning epoch. When unlearning a larger portion of the dataset, GUARD generally induces an even larger absolute reduction on the sacrifice rate across all evaluation sets (Retain Set, Real Author Set, and Real World Set) and methods (GA, GD, KM, and PO). On the Retain Set, GUARD lowers ρr by 19.38% over PO, ρp by 30.48% over PO, and ρt by 20.64% over GA.
Methods
Forget Set VerbMem
Forget Set KnowMem
PrivLeak
Retain Set KnowMem
( ↓ )
( ↓ )
( ∈[−5%,5%] )
( ↑ )
BOOKS
w/o Unlearn
99.8
59.4
-57.5
66.9
GA
0.0
0.0
-25.4
0.0
GA + GUARD
0.0
0.0
-31.0
10.6
KM
15.7
22.3
-39.5
36.2
Appendix
Table 12: Unlearning experiments with ICLM-7B on the MUSE BOOKS dataset under the official MUSE protocol; “w/o Unlearn” is the released MUSE BOOKS target model.
Dataset
Model
Forget set
GA (min)
GA + GUARD (min)
Attribution (min)
Overhead
TOFU
LLaMA-2-7B
1%
4.2
5.1
0.9
21.4%
5%
14.4
16.6
2.2
15.3%
10%
32.3
35.5
3.2
9.9%
Phi-1.5B
1%
2.8
3.0
0.2
7.1%
5%
6.1
6.8
0.7
11.5%
10%
14.5
15.6
1.1
7.6%
Appendix
Table 13: Per-epoch runtime of unlearning with and without GUARD, measured under the official TOFU and MUSE protocols. Attribution is the difference between the two runtimes, and Overhead is Attribution relative to the GA runtime.
Methods
MUSE NEWS (LLaMA-2-7B)
MUSE BOOKS (ICLM-7B)
Forget VerbMem
Forget KnowMem
PrivLeak
Retain KnowMem
Forget VerbMem
Forget KnowMem
PrivLeak
Retain KnowMem
( ↓ )
( ↓ )
( ∈[−5%,5%] )
( ↑ )
( ↓ )
( ↓ )
( ∈[−5%,5%] )
( ↑ )
NPO
1.5
44.8
93.0
37.2
0.0
0.0
-32.0
24.3
RMU (full retain, reference)
1.5
44.0
95.0
43.1
0.0
0.0
-36.1
47.8
NPO + GUARD (full retain)
1.6
45.2
98.2
50.0
0.0
0.0
-38.4
52.4
NPO + GUARD ( 20% retain)
1.6
45.4
97.5
47.6
0.0
0.0
-37.1
49.0
Appendix
Table 14: Robustness of GUARD under limited (random 20% ) and synthetic (GPT-4 generated, with no original retain data used in the attribution) Retain Sets on MUSE NEWS (LLaMA-2-7B) and MUSE BOOKS (ICLM-7B), at the early-stopping checkpoint under MUSE’s official protocol. RMU is included at full retain access as a reference point for the strongest competing baseline. As on TOFU (Table 5 ), both GUARD ablations preserve most of full-retain GUARD ’s Retain KnowMem gain over NPO; on NEWS, the synthetic-retain variant already outperforms RMU at full retain access, and on BOOKS it remains comparable. Bold marks the column-wise best across all rows; PrivLeak is reported for completeness (values closer to 0 are preferred).
Figure 4: Raw Score and Inverse unified score under different temperatures τ for the 40 samples of the TOFU forget01 split (Phi-1.5B), ordered by score (gradient-product attribution, exponential unification).
Methods
Retain Set( ↓ )
Real Author Set( ↓ )
Real World Set( ↓ )
ρr
ρp
ρt
ρr
ρp
ρt
ρr
ρp
ρt
NPO + ES
26.53
9.04
-12.54
19.60
10.20
-17.40
4.80
4.10
-14.30
NPO + RelatIF
22.08
6.35
-9.85
17.40
9.10
-14.50
4.10
3.50
-13.10
NPO + RIF
19.08
4.52
-8.50
16.20
8.70
-13.20
3.60
3.20
-12.30
NPO + GUARD
14.32
2.87
-6.10
13.59
7.14
-10.44
2.70
2.23
-10.29
Appendix
Table 15: Comparison of the performance of different attribution methods integrated with NPO on the TOFU benchmark (LLaMA-2-7B, 10% forget split) under the official TOFU protocol; values reported at the final ( 5 -th) unlearning epoch. GUARD outperforms both the feature-based baseline (ES) and other first-order influence approximations (RelatIF, RIF) across all evaluation sets in ρr and ρp . The substantially lower sacrifice rates on the Retain Set demonstrate that the gradient-alignment strategy of GUARD minimizes unintended harm to preserved knowledge more effectively than alternative attribution metrics.
Methods
Retain Set
Forget Set
ROUGE-L ( ↑ )
Prob. (%) ( ↑ )
T.Ratio ( ↑ )
ROUGE-L ( ↓ )
Prob. (%) ( ↓ )
T.Ratio ( ↑ )
NPO + ES
81.50
93.50
49.20
34.20
38.80
65.40
NPO + RelatIF
84.30
95.10
48.80
33.90
38.50
65.10
NPO + RIF
86.20
96.20
48.60
33.70
38.30
64.90
NPO + GUARD
89.30
97.20
48.30
33.80
38.20
65.20
Appendix
Table 16: Comparison of absolute performance metrics between GUARD and alternative attribution methods integrated with NPO, under the official TOFU protocol; values reported at the final ( 5 -th) unlearning epoch. Per-metric arrows follow TOFU ( Maini et al., 2024 ) . While all methods achieve comparable forgetting strength on the Forget Set, GUARD delivers the highest Retain ROUGE-L and Probability.
Machine unlearning removes the influence of selected data or concepts from trained models while preserving useful behavior and avoiding full retraining.