The plan was to begin production in June for a planned release date on the MLK holiday in 2012, and Universal says that there were concerns about Greengrass' ability to deliver the film in eight months. This sounds reasonable, particularly given that his last effort, Green Zone, endured numerous delays and reshoots before hitting theaters to an underwhelming reception.
In his exclusive on Universal's decision, Mike Fleming at Deadline mentions anonymous sources claiming that the the estate of Martin Luther King Jr objected to the screenplay, written by Paul Greengrass and based upon his own research. Fleming's source asserts that the King family threatened to go public with their displeasure over the project. If this is the case, it's not known whether their objections are based on the possible content, or the family's endorsement of a biopic written by Ronald Harwood and being developed at DreamWorks.
Memphis would focus on a less-known period in Dr. King's public and personal life as he attempted to organize the titular city's sanitation workers in 1968. By this time, MLK's espousal of broad social and economic reform had lost him many political allies, and his vocal condemnation of the Vietnam War put him into direct opposition with his former ally, President Lyndon Johnson. Apparently, his marriage was under tremendous strain, as well.
Greengrass and producer Scott Rudin are now shopping Memphis to other potential studios. If the schedule was the motivating factor in Universal's decision, a competing studio might just acquire the project. With United 93, Greengrass demonstrated an ability to quickly assemble a quality film, so another company could make a leap of faith. If, however, this was a result of displeasure from the estate and close associates of Martin Luther King Jr, then Memphis is unlikely to ever find a new benefactor.