Los Angeles ( CNN ) -- A lawyer for Michael Jackson 's estate gave an entertainment industry consultant permission to help AEG Live in its defense of the wrongful death lawsuit filed by the pop singer 's mother , the expert testified . The revelation was a surprise to Katherine Jackson , who was sitting in court Tuesday listening to the expert testify that he believed her son would not have earned any money even if he had not died of a propofol overdose . If jurors decide AEG Live is liable in Jackson 's death , testimony by Eric Briggs -- whose company billed the concert promoter $ 700,000 to prepare his opinion -- could be used to determine how much in damages the company would have to pay to Michael Jackson 's mother and three children . Briggs , however , previously consulted for the Jackson estate in determining a value of it 's biggest asset -- the Sony-ATV music catalog that includes the Beatles songs . He testified that before he signed a contract to serve as an expert in AEG Live 's defense he sought and gained permission from the Jackson estate lawyer Jeryll Cohen to waive any potential conflict of interest . `` She ( Cohen ) was well aware of everything that was going on , '' Briggs testified . A spokesman for the Michael Jackson estate was unaware of the circumstances or reasons why the estate would approve the waiver that could be counter to the interests of its beneficiaries -- Jackson 's mother and three children . Bad news hurt Jackson 's earning potential , witness says . An entertainment industry analyst hired by Jackson lawyers testified he was `` reasonably certain '' Jackson would have earned $ 1.5 billion from touring before retiring if he had not died while preparing for his comeback concerts in 2009 . Briggs testified that it was `` speculative '' that Jackson would have even completed the 50 `` This Is It '' concerts that AEG Live had already sold out in London . Briggs said that based on what he 'd learned from testimony in the case , he believed that Jackson would have died before the first show -- even if he had not suffered the fatal overdose of a surgical anesthetic on June 25 , 2009 . He cited the testimony of a doctor who said that Jackson would have been dead within a week if he remained under the care of Dr. Conrad Murray . The Jackson lawsuit contends AEG Live is liable in Jackson 's death because it negligently hired , retained or supervised Murray , who was convicted of involuntary manslaughter in the pop icon 's death . The Erk opinion included $ 300 million that he estimated Jackson would have earned from endorsements and sponsorships . But Briggs testified that `` significantly negative headlines , drug abuse and other issues '' had ruined Jackson 's ability to earn endorsement and sponsorship money . `` Q score '' data for Jackson , which measures his `` likability , '' became dramatically negative by 2006 -- a year after he was acquitted in a child molestation trial , he testified . More than seven people said they disliked Jackson for every one who said they liked him , he said . Companies would be `` very anxious '' about putting someone with such a negative `` likability '' next to their products , he said . Jackson 's drug use explored in trial . One issue hurting Jackson 's endorsement deal potential was his financial debt , estimated to be $ 400 million at the time of his death , Briggs said . But Jackson lawyer Brian Panish asked Briggs if he considered that Jackson 's assets -- most notably the Sony-ATV catalogue -- were greater than his debts . Briggs stuttered on the witness stand , saying he was reluctant to discuss Jackson 's assets because of a client confidentiality issue . He eventually acknowledged that he had worked for the Jackson estate as a consultant analyzing the value of the music catalog . He signed a confidentiality agreement with the estate , which he said prevented him from discussing it . His company did , however , clear his participation in the wrongful death case with a Jackson estate lawyer before he agreed to be an expert for AEG Live , he said . Briggs also said AEG Live lawyers were aware of the potential conflict before hiring him and had no problem with it . Wednesday is the 60th day of testimony in the trial , which began 14 weeks ago in a Los Angeles County court . The judge told jurors she expects testimony to conclude in mid-September . Celine Dion 'bigger than MJ ' ?
Katherine Jackson learns a consultant for her son 's estate is helping defend AEG Live . Michael Jackson 's mother is suing Group Live , claiming it 's liable for her son 's death . Consultant Eric Briggs says the estate approved his work for AEG Live 's defense . Briggs worked for the Jackson estate in the past .