In 1970, NBA legend Oscar Robertson filed a class action suit against the league along with 13 other players, including Celtics great John Havlicek and future U.S. Senator Bill Bradley. Similar to the case brought against MLB the same year by Curt Flood, which eventually reached the Supreme Court, Robertson's lawsuit challenged the NBA's limitation on player movement through the reserve clause. Oscar Robertson v. National Basketball Association was settled in 1976, paving the way for the "Oscar Robertson Rule" and free agency.

The NBA still has means to discourage unfettered player relocation – for example, a restricted free agent's current team can match any offer for him, and it has a higher years and dollars threshold for unrestricted free agents than any other team. That's why you hear all the talk about the Los Angeles Lakers being able to offer Dwight Howard five years and $118 million, while the Houston Rockets and Dallas Mavericks can only offer four years and $88 million (though Texas has no state income tax).

Here is a look at some players who chose to depart their previous teams and made a seismic impact in doing so. Free agency has a history of almost four decades, but the list is a little less glamorous than one may assume.