III.4.b.

Engineers shall not, without the consent of all interested parties, participate in or represent an adversary interest in connection with a specific project or proceeding in which the Engineer has gained particular specialized knowledge on behalf of a former client or employer.

Code is relevant when:

Engineer participates in a project or proceeding for Client 1 (a former client)
AND
Engineer participates in a project or proceeding for Client 2 (a current client)
AND
Client 1 and Client 2 are adversaries

Code is violated when:

Engineer does not have consent from all interested parties
AND
Engineer has gained particular specialized knowledge on Client 1's project and that knowledge could be used in the project with Client 2.

Code is not violated when

Engineer has consent from all interested parties
OR
Engineer has not gained particular specialized knowledge on Client 1's project and that knowledge could be used in the project with Client 2.