Macdonald Scott, who represents two of the people arrested, said Canada Border Services Agency officials aggressively demanded identification from members of visible minorities during the four-hour operation last Thursday.
CBSA defended its participation in the traffic blitz, which also involved the Ontario Ministry of Transport and provincial police, but did not comment on the racial profiling allegations.
"In the past, the CBSA has been invited to participate in this type of blitz when partner agencies have noticed that many drivers stopped during blitzes had immigration warrants," the agency said in an email to The Canadian Press.
"As a result, it was determined that the CBSA's presence would be beneficial in the processing of these individuals."
Scott said the arrests took place in an area where construction labourers wait to be picked up by potential employers. He said both his clients are Mexican men in their early 20s and work in construction.
"One guy was just walking over to visit a friend," he said. "They pressured him into giving his name, found out he has an immigration warrant and basically detained him."
His other client was a passenger in a van when he was stopped while on his way to work with five to six other people, Scott said.
"It's racial profiling," he said. "I asked my clients, 'Do you see them stopping white people?' They said, 'No, they're only stopping Latinos.'"
Scott said both men were deported Tuesday.
Sharry Aiken, associate dean of Queen's University's law faculty, said people only need to provide identification to border officials operating inland if they are suspected of committing an immigration offence — something hard to establish by observation.
"If Canada Border Services Agency tried to suggest that, 'I have reason to believe this is an illegal migrant... because they're Irish, and we happen to know that there're a lot of illegal workers from Ireland' — sorry, that doesn't cut it," she said.
Steven Tress, an immigration lawyer in Toronto, said even if the driver is an illegal immigrant, passengers should not be under suspicion simply by association.
"You're driving with a friend and he's here illegally... If the CBSA or the police want to arrest that person, that doesn't require you to identify yourself," he said.
The migrant advocacy group No One Is Illegal protested the arrests on Monday outside government buildings in Toronto.
Group organizer Syed Hussan said the group has made contact with seven of those arrested, among whom there are four from Mexico and one each from Argentina, El Salvador the Philippines.
The provincial police said its involvement in the operation was limited to sending one officer to attend a briefing, while the Ministry of Transport said it only focuses on vehicle violations.
Federal Citizenship and Immigration Minister Chris Alexander defended the CBSA involvement in the blitz, saying those "out of status" who want to avoid an "unpleasant turn of events" should either try to attain immigration status or leave the country.
"CBSA does its job extremely well, removing large numbers of those who have abused Canada's generosity," he said on Tuesday.
"From what I've heard, that was the case in recent days in Toronto with the people that were arrested — undocumented workers — by CBSA."