MLO-44Required
Remove erased people from every model trained on their data
When a person's data must be erased, drop their rows from every snapshot used for future training. Retrain each model that learned from them within a set time, such as 90 days, unless its membership test shows it holds no personal data.
How to do it
Deleting the source row does not remove what a model learned. A model that is not anonymous is personal data itself, so erasure reaches it too. Keep a list of erased person keys, and filter it out of every new snapshot, as freeze each training set as a versioned snapshot allows. Map each person key to the snapshots and models that used it. A model that passes test that the model does not give away its training records may wait for its next scheduled retrain. Others retrain within the set time. Methods that make a model forget without retraining are still research, so do not rely on them alone. Language model stores follow erase a person's data from every AI store.
Examples
Python example
def build_snapshot(rows: pd.DataFrame, erased_keys: set[str]) -> pd.DataFrame:
return rows[~rows["person_key"].isin(erased_keys)]
def models_due_for_retrain(models: list[ModelVersion], today: date) -> list[ModelVersion]:
return [m for m in models if m.has_erased_rows and not m.membership_test_passed
and (today - m.first_erasure_date).days > ERASURE_RETRAIN_DAYS]
TypeScript example
export function buildSnapshot(rows: TrainingRow[], erasedKeys: Set<string>): TrainingRow[] {
return rows.filter(row => !erasedKeys.has(row.personKey));
}
How to check
A test erases a person and builds a new snapshot, and none of their rows appear in it. A script lists every production model trained on a snapshot holding erased rows. It fails when one is older than the set time and has no passing membership test.
Sources
Related rules
- MLO-6 Freeze each training set as a versioned snapshot in Machine learning
- MLO-41 Test that the model does not give away its training records in Machine learning
- AIF-51 Erase a person's data from every AI store in AI features
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