The most common claim of discrimination falls under the heading of “indirect”.
The legal meaning of indirect discrimination is where an employer applies a provision, criterion or practice which places a person with a protected characteristic at a disadvantage and the employer cannot show that the provision criterion or practice is a proportionate means of achieving a legitimate aim.
What this means in practice is that where you have a policy in place that applies to all employees, but which disadvantages some, you are at risk of an indirect discrimination claim unless you can justify the policy.
For example, a policy that says you won’t allow any employee to work part-time will affect more women than men, as they are more likely to want to work part time because of their childcare responsibilities. If you can’t justify that policy, it will be discriminatory.