The tribunal ruled Friday that Thrifty Foods discriminated against Sharon Mackenzie when it dismissed her for behaviour including mood swings and irritability with her managers.
"Thrifty's had a duty to inquire into whether the behaviour exhibited by Ms. Mackenzie was due to her mental disability and whether she required any accommodation," tribunal member Catherine McCreary wrote in the ruling.
"They did not fulfill that duty."
Mackenzie began working for the store's floral department in 2001. She was terminated in fall 2009, and filed a complaint with the tribunal in April 2010.
The ruling says the woman suffered depression most of her life, and was treated with medication and cognitive therapy.
The store told the tribunal it dismissed the woman because she was curt and abrupt with co-workers and management, was considered to be gossipy and manipulative, and she refused to take responsibility for such behaviour.
Mackenzie reported being able to manage her life outside the workplace, with most of the stressors occurring at the store.
"It is the employer's responsibility to obtain relevant information about the employee's current medical condition, prognosis for recovery, ability to perform job duties and capabilities for alternate work," McCreary wrote.
The tribunal found that Thrifty's and a store manager, Lisa Trotter, knew Mackenzie suffered from depression and was taking medication as treatment.
Trotter reported that Mackenzie was sometimes "tearful" in meetings, but said she did not find this unusual because "she experienced many employees crying during her interactions with them."
Mackenzie left work on "stress leave" for two months in summer 2009. She was fired several months later.
The tribunal has ordered the store to pay Mackenzie more than $17,600 for lost wages and $5,000 for injury to dignity.
It has also been ordered to refrain from committing the same discriminatory act in the future.