A technology in the past, the buyer’s agent had all the information — comparable neighborhood sales prices, tax histories, faculty district placement and particulars of the house — and was imagined to act as a complete counselor. The case hinged on the commissions, usually of 6%, that sellers pay their agents, who then cut up them with the buyers’ brokers. It has been a cornerstone of how the NAR — a strong commerce group of 1.5 million members — does business. But after just hours of deliberation, a jury found that this standard trade practice quantities to collusion to inflate …