TORONTO - Disgraced Olympic sprinter Ben Johnson plans to sue his former lawyer's estate for $37 million, alleging that Edward Futerman took advantage of his "diminished mental capacities" in "an arrogant, high-handed and negligent conduct."

Johnson filed a notice of motion with the Ontario Superior Court of Justice on Thursday asking to amend a statement of claim that was filed last year, in which he asked for $9 million in damages.

Johnson is to make the motion in October to enter an amended statement of claim, which alleges the late Futerman "ambushed and scooped" him into signing a retainer when he returned to Canada after winning the gold medal in the 100-metre dash at the 1988 Seoul Olympics, only to be disqualified days later after failing a drug test.

In the amended statement of claim, Johnson is seeking $20 million for breach of contract, $12 million for negligence and $5 million for punitive damages.

According to the claim, the retainer - that Johnson was unable to understand and hurried into signing - granted the lawyer "absolute and improper" control over Johnson's career and finances.

Johnson also alleges Futerman hired another client, hairdresser Kameel Azan, to act as the sprinter's sports agent.

The statement claims that Futerman "negligently acted for his own and (Azan's) personal financial gain by ensuring that Ben did not have an experienced family member to assist Ben and oversee all of his matters."

Last year Johnson, 46, also filed a statement of claim against Azan for more than $6 million.

In the claim against Azan, the sprinter alleged that Azan abused authority, endangered Johnson's ability to earn income and mismanaged Johnson's financial affairs.

It goes on to claim that Azan diverted funds to personal bank accounts other than Johnson's, paid unauthorized invoices and received duplicate commissions.

"The negligence and dishonesty of the defendant has caused the plaintiff considerable financial hardship, personal stress and inconvenience," the statement read.

None of the allegations in either statement of claim have been proven in court.

In the amended statement of claim against Futerman's estate, Johnson alleges the lawyer knew Azan had no experience and was "totally out of his depth in this very sophisticated international sports arena."

Johnson claims Futerman authorized unearned commissions to Azan totalling more than US$240,000 and that US$750,000 is still unaccounted for.

He also claims that Futerman dismissed invitations for Johnson to attend lucrative media and sports promotion opportunities, including a rematch against arch-rival Carl Lewis in Las Vegas that would have potentially earned him more than US$3 million.

Johnson filed the initial statement of claim in March 2007 representing himself. He has since retained lawyer Robert Hopkins. Johnson claims he became aware of a number of the alleged financial improprieties following research conducted for a biography.

In a statement of defence filed in response to the 2007 claim, Futerman says the legal retainer was restricted to negotiating contracts for Johnson and he never acted as manager, financial adviser or trustee in relation to an account which Johnson claims money went missing from.

It further refutes that any money was mismanaged or improperly paid out, denying that Johnson suffered any damages and claiming Futerman actually suffered damages due to Johnson's "conduct and decisions."

"This claim is frivolous, unmeritorious, and an abuse of process of this honourable court," the statement reads.

Futerman died in February 2008 but the case has since been ordered to proceed with his estate as the defendants.

A psychiatric evaluation of Johnson included in the court file describes him as "as dependent on adult direction and advice as the average six-or seven-year old."

Johnson was born in Jamaica. He competed twice for Canada in the Olympics, winning a bronze in Los Angeles in 1984 and the gold - which was stripped days later after drug tests showed he'd taken steroids - in Seoul. He now lives in the Toronto area.