The controversial issue of transparency between brand marketers and their advertising agencies appears to be at, or very near, a tipping point — but the journey has been slow and torturous.

At the heart of the long-simmering dispute has been the extreme lack of transparency around media buying and the nature of the relationship between agencies and the brands they (are supposed to) serve. This was detailed at length in the ANA/K2 Intelligence report released two years ago. But transparency is just a symptom, says attorney Douglas Wood, a partner in Reed Smith LLP and the leader of the firm's advertising and marketing law practice. "The real issue is trust, because the law can only do so much," he says.

At a certain point, contracts designed to enforce transparent practices on agencies serving clients can become "overbearing," says Wood, who is also the ANA's general counsel. When that happens, he says the contract "doesn't help build a relationship, it's actually destructive to relationships. That's not an outcome anyone wants, but the less you trust someone, the more you need to rely on the contract to provide a substitute for trust."