Stella English sued Sugar after resigning from the £100,000 a year job, complaining she was treated like an "overpaid lackey".
According to Martin Pratt, employment lawyer at law firm Lester Aldrige, it is "unsurprising" English lost her case. He said an employer has "no obligation" to provide an employee with something to do.
"By her own evidence, she seems to have effectively admitted to the tribunal that her role was redundant," he said.
"On that basis the tribunal was unlikely to find that her contract had been breached and that she was thus entitled to resign and claim constructive dismissal.
"Even if they had, it is quite possible that her damages would have been minimal on the grounds that she was immediately offered another job by Lord Sugar after her resignation and, even if she hadn't taken the new role, she would have been made redundant within a short period of time anyway. All in all, it looks like she had a pretty poor case."
During the case, Sugar told the employment tribunal at the East London Tribunal Centre he had no case to answer and English was effectively blackmailing him.
In a written judgment, Judge John Warren said: "This was a claim which should never have been brought.
"There was no assurance or suggestion that the winner would receive direct mentoring from Lord Sugar.
"The claimant was clear herself about this - she knew full well the job she would do at Viglen when she accepted the prize. She told the nation on the BBC Breakfast TV show."
He said English had the wrong idea about how glamorous the role would be and had stated in her evidence that she believed previous winners of the show "had accompanied Lord Sugar in his private jet".
"The tribunal believes that the claimant had in her mind that having won The Apprentice the role would be much more glamorous and that she would be working alongside Lord Sugar as his assistant," Warren said.
Employment law specialist and senior lecturer at The University of Law, Amanda Hedayati said: "This case serves as a reminder that claims for constructive dismissal are notoriously difficult to win.
"Even in circumstances where an employee had been subjected to unreasonable behaviour by their employer, this is not necessarily sufficient to demonstrate the required seriousness of breach of a key term of contract.
Hedayati said: "Of course, more extreme cases of unreasonable behaviour and bullying will still pose a risk to the employer that the conduct will amount to constructive dismissal. Many situations like that which English reports will be considered to fall into the category of the usual highs and lows of the workplace.
"Given that the individual will have had to resign in order to bring the claim, in the current climate, where it might be some time before the employee can get another job, the tribunal route can be very risky indeed."
