The elder Jones made a brief statement following the decision.
"Just because you're in public office does not mean you're a second class citizen, and I respect fathers to take care of their children. So will I support my son? Sure, I'm going to support my son," he said.
But there are critics who call it political nepotism.
The retiring senate president has not said much about why he will not stand for re-election and even less about his moves to have his son take his place on the November 4 ballot.
"I don't know him. I've never met him. And I'm sure he's a fine person," said Rep. Monique Davis, (D) Chicago.
Davis is one of the two state representatives who serve within the 14th state senatorial district that includes parts of the city and south suburbs. Davis said she never met the younger Jones, and if she saw him on the street she wouldn't recognize him:
"I think there's some other people perhaps who could better represent us in that senate seat," Davis said.
In a weighted vote, the Democratic committee members from within the senatorial district decided who will replace Jones on the fall ballot. Thirty-fourth Ward Alderman Carrie Austin had the most votes.
"I believe that the information and knowledge that he has gleaned from his father makes him a great candidate," Austin said.
Emil Jones III, who did not finish college, works as a $60,000 a year account manager for the state's Department of Commerce and Economic Development. If he is selected to run, he would face perennial Republican candidate Ray Wardingly, who made a name for himself several years ago playing Spanky the Clown.
The Jones post-primary, hand-the-office-off-to-a-family-member plan, is reminiscent of events that led to Dan Lipinski's 2004 election to succeed his father, Bill, in Congress:
"I think it's really the news media? the only ones who focus on anything that happened four years ago," said Rep. Dan Lipinski, (D) Chicago.
Davis complained that the elder Jones, by announcing his retirement Monday, did not leave other prospective candidates time to mount a campaign for the nomination - other candidates, like her own son:
"He worked with me and Harold Washington and worked in government. He was a researcher. And he's also a former staffer for (house) speaker (Michael) Madigan," Davis said.
Emil Jones III has never before faced reporters in a political campaign. But minutes after being chosen by the Democratic committee to run in place of his father he jumped right in and immediately faced questions about nepotism.
"I did not get in through the back door. I am officially on the ballot and will run in the election on November 4," said the newest 14th District state senate nominee.
The district's registration is overwhelmingly Democratic. And that's why critics question Emil Jones Jr.'s timing. .
"You can't ask for respect of the public when you are clearly gaming the system for the benefit, not of the public, not even of your own party, but for your family," said Jay Stewart, executive director of the Better Government Association.
Senator Jones has yet to explain the timing of his retirement announcement, which follows the primary election but leaves enough time to get a new name on the ballot. But he insists his son is well qualified for the job. And he makes no apologies about putting him forward as a candidate.
Lieutenant Governor Pat Quinn says by putting a son in place, Senator Jones is doing what Lipinski and Cook County Board President John Stroger, among others, have done. He said he believes it's wrong.
"I think voters ought to have much more of say-so in an election contest to nominate who they want," Quinn said.