Enabling access, erasure, and rectification rights in AI systems

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Enabling access, erasure, and rectification rights in AI systems

Reuben
Binns, our Research Fellow in Artificial Intelligence (AI), discusses the
challenges organisations may face in implementing mechanisms in AI systems that
allow data subjects to exercise their rights of access, rectification and
erasure.


This post is part of our ongoing Call for Input on developing the ICO framework for auditing AI. We encourage you
to share your views by leaving a comment below or by emailing us at 
AIAuditingFramework@ico.org.uk.
Under
the General Data Protection Regulation (GDPR) individuals have a number of
rights relating to their personal data. These rights apply to personal data used
at the various points in the development and deployment lifecycle of an AI
system, including personal data:

  • contained
    in the training data;
  • used
    to make a prediction during deployment; or
  • that
    might be contained in the model itself.

This
blog post describes the considerations organisations may encounter when
attempting to comply with three specific rights – access, rectification and
erasure – in relation to AI systems, and where exemptions may apply.

Rights relating to training data

Organisations
that create machine learning (ML) models will invariably need to obtain data to
train those models.

For
instance, a retailer creating a model to predict consumer purchases based on
past transactions will need a large dataset of customer transactions on which
to train the model.

A
potential challenge for fulfilling individuals’ rights is the difficulty involved
in identifying the individuals the training data relates to.

Right of access

Typically,
training data only includes information relevant to predictions, such as past
transactions, demographics, or location, but not contact details or unique
customer identifiers.  Training data is also
typically subjected to various ‘pre-processing’ measures to make it more
amenable to ML algorithms.


For instance, a detailed timeline
of a customer’s purchases might be transformed into a summary of peaks and
troughs in their transaction history.

This
means training data can be much harder to link to a particular individual.
However, in relation to data protection law this cannot be considered in itself
to be pseudonymisation or anonymization, and the data must still be considered
when responding to individuals’ requests under the GDPR.

However,
even if it lacks associated identifiers or contact details, and has been
transformed through pre-processing, training data may still be considered personal
data, because it can be used to ‘single out’ the individual it relates to, on
its own or in combination with other data (even if it cannot be associated with
a customer’s name).

For
instance, the training data in a purchase prediction model might include a pattern
of purchases unique to one customer.

In this example, if a customer were
to provide a list of their recent purchases as part of their request, the organisation
may be able to identify the portion of the training data that relates to that
individual.

In
these kinds of circumstances, the organisation is obliged to respond to a data
subject’s request, assuming they have taken reasonable measures to verify the
identity of the data subject, and no other exceptions apply.

Requests
for access, rectification or erasure of training data should not be regarded as
manifestly unfounded or excessive just because they may be harder to fulfil or
the motivation for requesting them may be unclear in comparison to other access
requests an organisation typically receives.

Organisations
do not have to collect or maintain additional personal data to enable
identification of data subjects in training data for the sole purposes of
complying with the regulation (as per Article 11 of the GDPR). There may be times,
therefore, when the organisation is not able to identify the data subject in
the training data (and the data subject cannot provide additional information
that would enable their identification), and therefore cannot fulfil
 a request.
Right to rectification

The
right to correct inaccurate data may also apply to training data. However, the
purpose of training data is to train models based on general patterns in large
datasets, so individual inaccuracies are less likely to have any direct effect
on an individual data subject. Organisations should therefore prioritise the
rectification of personal data that might be used to take action in relation to
an individual, over training data whose accuracy at an individual level is less
likely to affect the individual.

Returning to our example, it may
be more important to rectify an incorrectly recorded customer delivery address
than to rectify the same incorrect address in training data. This is because the
former could result in a failed delivery but the latter would barely affect the
overall accuracy of the model.

Right to erasure

Organisations
may also receive requests for erasure of training data. Organisations must respond
to requests for erasure, unless a relevant exemption applies and provided the
data subject has appropriate grounds. For example, if the training data is no
longer needed because the ML model has already been trained, the organisation must
fulfil the request. However in some cases, where the development of the system
is ongoing, it may still be necessary to retain training data for the purposes
of re-training, refining and evaluating an AI system. In this case, the
organisation should take a case-by-case approach to determining whether it can fulfil requests.

Complying
with a request to delete training data would not entail erasing any ML models
based on such data, unless the models themselves contain that data or can be
used to infer it (situations which we will cover in the section below).

Rights relating to personal data involved in AI systems during deployment

There
are only a few differences between the considerations that apply to training
data and the personal data involved during model deployment.

Typically,
once deployed, the outputs of an AI system will be stored in a profile of an
individual and used to take some action in relation to them.

For instance, the product offers
a customer sees on a website might be driven by the output of the predictive
model stored in their profile. Where such data constitutes personal data, it would be subject to the rights of access,
rectification, and erasure. Whereas individual inaccuracies in training data
will usually have only a negligible effect, an inaccurate output of a model could
directly affect the data subject.
 

Requests for rectification of model outputs
(or the personal data inputs on which they are based) are therefore more likely
to be made, and should be treated with a higher priority, than requests for
rectification of training data.

Rights relating to the model itself

In
addition to being used in the inputs and outputs of a model, personal data
might also be contained in a model itself. As
explained in a previous blog post Privacy
attacks on AI models
, this could happen for
two reasons; by design or by accident.

Fulfilling requests about
data contained by design

When
personal data is included in models by design, it is because certain types of models,
such as Support Vector Machines (SVMs), contain some key examples from the
training data in order to help distinguish between new examples during
deployment. In such cases, a small set of individual examples will be contained
somewhere in the internal logic of the model.

The
training set would typically contain hundreds of thousands of examples, and
only a very small percentage of them would end up being used directly in the
model. Therefore, the chances that one of the relevant data subjects makes a
request are very small; but it is possible.

Depending
on the particular programming library in which the ML model is implemented, there
may be a built-in function to easily retrieve these examples. In such cases, it
might be practically possible for an organisation to respond to a data
subject’s request. If the request is for access
to the data, this could be fulfilled without altering the model. If the request
is for rectification or erasure of the data, this would not be
possible to achieve without having to re-train the model (either with the rectified
data, or without the erased data), or deleting the model altogether.

Fulfilling requests about
data contained by accident

Aside
from SVMs and other models that contain examples from the training data by
design, some models might ‘leak’ personal data by accident. In such cases, unauthorised
parties may be able to recover elements of the training data or infer who was
in it by analysing the way the model behaves.

The
rights of access, rectification, and erasure may be difficult or impossible to exercise
and fulfil in these scenarios. Unless the data subject presents evidence that
their personal data could be inferred from the model, the organisation may not be
able to determine whether personal data can be inferred and therefore whether the
request has any basis.

Organisations
should regularly and proactively evaluate the likelihood of the possibility of personal
data being inferred from models in light of the state-of-the-art technology, so
that the risk of accidental disclosure is minimised.

Your feedback

We would like to hear your views on this
topic and genuinely welcome any feedback on our current thinking. Please share
your views by leaving a comment below or by emailing us at AIAuditingFramework@ico.org.uk

Dr Reuben Binns, a researcher working on AI and data protection, joined the ICO on a fixed term fellowship in December 2018. During his two-year term,

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