http://www.sacbee.com/2013/01/20/5126810/nba-rarely-blocks-teams-from-moving.html#storylink=misearch
As Mayor Kevin Johnson tries to keep the Sacramento Kings from moving to Seattle, he can take heart from the story of the Minnesota Timberwolves. The NBA prohibited the team from moving to New Orleans in 1994. It's believed to be the last time the NBA rejected a formal relocation request.
The NBA even sued the Timberwolves to make sure they stayed put. The team eventually sold to local owners.
"The NBA told them, 'Look for other buyers,' and they did," said attorney Elliott Kaplan, who represented the NBA in the case.
On June 15, 1994, the NBA's relocation committee, an enormously influential group consisting of six team owners, voted unanimously to block the sale.
The committee's vote was enough for Stern to declare the Timberwolves weren't moving. The full board of governors ratified the panel's recommendation a week later. To make sure, the NBA sued the Timberwolves and Top Rank to get an injunction blocking relocation.
"Sometimes we have lawsuits in a drawer for special occasions – birthdays, weddings and franchise transfers," Stern said at the time.
It got messy for a while. Top Rank filed its own lawsuit in a Louisiana court. But the NBA prevailed, and the team was sold to a local owner.