May 17, 2022

Public at Risk of Discrimination From Online Behavioural Advertising, Says Oxford Legal Expert

From the Oxford Internet Institute:

Associate Professor, Dr Sandra Wachter, Senior Research Fellow at the Oxford Internet Institute highlights how techniques such as affinity profiling – grouping people together according to their assumed interests rather than solely their personal traits – has become common place in the online advertising industry, with advertisers increasingly able to target or exclude certain groups from products and services based on assumptions of what they think users want to see.

Professor Wachter makes the case that (indirect) discrimination in online behavioural advertising is typically very subtle.  For example, someone might have many LGBT+ friends on Facebook and is not aware that their own sexual orientation can be inferred based on their circle of friends. However, advertisers might use these – maybe inaccurate – assumptions (one might not identify as LBGT+) about someone’s’ sexuality and target or exclude them on that basis. This means both accurately and inaccurately profiled users potentially miss out on certain products and services based on their interests, habits or routines.

In her article, ‘Affinity Profiling and Discrimination by Association in Online Behavioural Advertising’ forthcoming in Berkeley Technology Law Journal, Professor Wachter presents an alternative legal concept to address structural bias in online advertising. This includes the case for applying the concept of ‘discrimination by association’.


The concept of ‘discrimination by association’ challenges the idea of strictly differentiating between assumed interests and personality traits when profiling people.

Instead the concept of ‘discrimination by association’ acknowledges that a person might be treated significantly worse than others based on their assumed relationship with a protected group without directly inferring details about that person and grants protection regardless if someone is a member of that group and if these inferences are accurate.

The paper sets out three ways in which adopting ‘discrimination by association’ could provide greater protection from structural bias within online behavioural advertising:

  • Greater protection against adverse actions by advertisers based on assumed interests, groupings or associations (e.g. interest in a culture) even if no personal traits are directly inferred about the person (e.g. assuming one’s ethnicity)
  • Protections for misclassified users that experience adverse effects
  • Greater protection for “accurately” profiled people because group membership is not necessary for protection. Someone with a gender identity, disability, or religious related legal claim would not need to “out” themselves to file a complaint.

Read the Complete Article Summary

Direct to Full Text Article: Affinity Profiling and Discrimination by Association in Online Behavioural Advertising

See Also: Publications by Dr. Wachter


About Gary Price

Gary Price ( is a librarian, writer, consultant, and frequent conference speaker based in the Washington D.C. metro area. Before launching INFOdocket, Price and Shirl Kennedy were the founders and senior editors at ResourceShelf and DocuTicker for 10 years. From 2006-2009 he was Director of Online Information Services at, and is currently a contributing editor at Search Engine Land.