The same year, he granted a visa to Italian au pair Michela Marchisio who was facing deportation for reportedly planning to work for a former Queensland police colleague.
Mr Dutton used his ministerial powers to stop the Border Force deporting the young women suspected of planning to work in Australia despite holding tourist visas.
In a statement to SBS News, Mr Dutton said he made "decisions on the merit of individual cases according to the law".
Ms Williams said while the moves were indeed legal, they were highly unusual.
"I haven't seen anything like this and I've been practicing close to 20 years. It's unprecedented," she said.
She said the ministerial intervention by Mr Dutton occurred "extremely quickly", which in Ms Marchisio's case was within several hours of being notified.
"Usually ministerial intervention takes months. We've got cases that have taken 12 months. In one instance, it was three years before the minister even looked at it."
Ms Williams questioned how all the appropriate processes, such as sourcing police and medical checks, were followed within such a short period.
"It's usually quite an extensive process. It takes a long time to get everything together and present a good case to the minister."
Others in 'much more need'
Ms Williams said individuals need to "put forward compassionate and compelling circumstances as to why their case should be overturned".
"[Currently] there are extreme humanitarian cases being turned back by the minister that have greater compassionate needs, such as visitor visas being refused for overseas family members wishing to visit their dying relatives or partners being separated."
"It's all very unusual and it's completely surprising. Other colleagues in the industry are all up in arms and can't believe it, when they've got current clients' files pending ... with people in much more need to have some form of ministerial intervention."
She summed up the minister's actions as "an appalling breach of standards".
'Best interests of the country'
But Mr Dutton has consistently defended his decisions.
"I make a decision that I believe is in the best interest of our country. I do it every day with visas," Mr Dutton told 2GB radio on Friday.
"That's the whole reason for ministerial intervention, because you believe the department has made a decision that is not right."
On Ms Deuwel's case, Mr Dutton said he acted because he thought it was a "bit rough" for a young woman with no criminal history to get kicked out of the country.
But Mr Dutton did so despite being told Ms Deuwel had previously been counselled in May 2015 after breaching visa conditions on an earlier visit.
Defence Minister Christopher Pyne has described concerns over the interventions as a "classic storm in a tea cup".
"I really don't think there is anything to see here," he told Nine on Friday.
No special treatment
AFL boss Gil McLachlan does not believe he got special treatment after lobbying Peter Dutton to overturn the deportation of a French au pair.
Mr McLachlan insists his only role in the 2015 incident was forwarding onto the then-immigration minister's office an email from his cousin.
"All I was doing was actually trying to help facilitate the contact, not make a representation," he told 3AW radio on Friday.
"I feel it was reasonable to have done so, others can make their assessments."
Mr McLachlan denies he got special treatment because of his public profile.
"That's a question for someone else but I don't think so," he told 3AW.
"I think this has just been treated on its merits, as the minister said."
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Additional reporting: AAP