ValueClick pioneered behavioural targeting after purchasing Be Free in 2002, a company that held two patents crucial to behavioural targeting.
ValueClick contends this means it owns the behavioural targeting technology Platform-A is using as a major selling point.
Prior to AOL's acquisition of Tacoda, a small Arizona-based firm, another behavioural targeting company, Modavox sued it for a similar patent infringement. Despite the ongoing case, AOL proceeded to close the acquisition of Tacoda for $275m.
This year, ValueClick brought similar cases against Blue Lithium and Revenue Science; both were settled out of court and involved significant payments to ValueClick.
ValueClick Media launches its Precision Behavioural Targeting product in the UK this week, following a successful US launch in July.
Richard Sharp, managing director, UK media and trading at ValueClick UK, said: "The Precision Behavioural Targeting suite will be able to deliver real-time targeted ads to consumers at relevant points in their transactional process."
Tacoda declined to comment.