Stanley had attributed his 2014 conviction to a failure to consider metabolism after drinking wine at lunch with a friend, something which was described as a lack of insight and concerned the High Court judge.
But Stanley, who had been an insurance broker, didn't give up on his bid to be a lawyer.
He took the case to the Court of Appeal and in April last year The appeal court agreed with him - but it prompted the Law Society to appeal in turn to the Supreme Court.
This led to a hearing in April, before the top court todayissued its ruling.
A majority of the Supreme Court, comprising Justice William Young, Justice Mark O'Regan and Justice Ellen France, dismissed the Law Society's appeal.
They said the concerns arising from Stanley's convictions were not a controlling factor given his otherwise good character, including the fact that he had led a productive life.
The majority also took into account the fact that, although the offending was of obvious concern, it had no direct connection with legal practice.
But Chief Justice Helen Winkelmann and Justice Susan Glazebrook dissented.
"Driving while impaired due to alcohol is inherently dangerous and can cause serious injury and death. It is thus very serious offending," they said in their reasons, provided by Justice Glazebrook.
"Multiple drink driving convictions would in many cases signal either a drinking problem, a contempt for the law, or both. In our view, both directly affect a person's ability to practise as a lawyer."
The pair said there must be a risk that a drinking problem could adversely affect a lawyer's judgment and thus their ability to serve their clients competently.
"Contempt for the law raises serious questions as to a lawyer's ability to fulfil their fundamental obligation to uphold and promote the rule of law."
The minority justices saw the lack of an expert report as fatal and said Stanley's own assertions about reform were an insufficient basis for the Court of Appeal's conclusion that his risk of reoffending was not high.
Despite this, Stanley can now work as a lawyer. He has been admitted as a barrister and solicitor and issued with a practising certificate.
The Supreme Court's judgment read: "We understand that the practising certificate was issued subject to voluntary undertakings from Mr Stanley requiring him, amongst other matters, to obtain the approval of the Law Society before accepting employment as an in-house lawyer."
In a similar case, former policeman Ethan James Brown failed in his bid to become a lawyer because of character grounds in 2018.
Brown had admitted sending inappropriate texts to a 13-year-old girl and was twice acquitted of sexual violation charges. After his trial, he resigned as a police office and studied criminal law.
However, he was denied a practising certificate after the High Court found he had not been open about his disclosures to police and didn't appreciate the inappropriateness of his conduct.
