COI is defined as follows:

Had at any time a supervisor/PhD student relationship.
Are both from the same institution, or have worked at the same institution in the past 3 years.
Are currently working together on a research paper or project, or have done so during the past 3 years.
Are related, or are close personal friends.
Are in some form of financial relationship, or have been at some point during the past 3 years.
Any other reason or circumstance that creates a risk that professional judgement may be unduly influenced.