The phrase refers to certain types of harassment or discrimination as set out in the Equality Act 2010, specifically those found under section 13 (direct discrimination), sections 15 to 19A (which include indirect discrimination, discrimination arising from disability, and pregnancy and maternity provisions), and section 26 (harassment).

For a matter to be treated as "relevant" under section 202A, the conduct in question must involve the employer or another person working for the employer. In addition, the individual affected must either be the worker making the disclosure or one of their co‑workers.