Grant said the charges against investigator Hilton Botha would have little if any impact on the Pistorius case, bearing in mind that in countries around the world, the testimony of convicted persons is used against fellow inmates.
"The defense would need to undermine his credibility as a witness, and I don't see how this shows that he is an untrustworthy witness," he said.
"The charges do not, in my view, undermine the credibility of the investigating officer as an honest witness relating to what he discovered at the Pistorius home. If the officer faced charges or had been convicted of crimes of dishonesty, that may well be a different matter."
Would Pistorius be given special treatment in prison if he was convicted and jailed?
CNN's team in Johannesburg understands the double amputee would not receive special treatment, with even blind prisoners being placed with sighted prisoners in South Africa.
But, ahead of his release on bail, the African National Congress Women's League said the athlete was already getting special privileges, adding that his family could visit him outside visiting hours, unlike relatives of other inmates.
"If Pistorius is denied bail, he must be moved to a proper prison facility with others accused of similar crimes," it said in a statement.
"A strong message must be sent out that wealth and celebrity cannot give you an advantage over the law."
What is the reputation of South Africa's legal system?
Grant said that South Africa was proud of its constitution and had a well-respected judiciary and that its substantive criminal law was "similarly advanced and progressive and very well considered."
"The problems that we're facing are more of a systemic procedural nature.
"We have an incredibly strained police force that's not particularly well-trained -- they're massively overloaded -- and we're struggling with issues of corruption within the police force and possibly even within the prosecution service," he said.
Grant said that, regrettably, wealthier South Africans had access to better legal resources than most of their compatriots.
"Unfortunately, most South Africans don't have that extent of resources available to them. They wouldn't have available to them the best possible defense lawyers, but in a strange sense, this is not a problem unique to South Africa. Money buys for you a degree of protection. That's of course a universal problem."
In March, the South African government's midterm report noted that "The effectiveness and ability of the criminal justice system to serve as a deterrent against crime is unfortunately still under threat of being undermined by the actions of a small number of those who serve in it."
It continued, "Since 2009, investigations have uncovered 1,529 persons in the criminal justice system who were possibly involved in corruption-related crime.
"For the year April to September 2011, 192 officials were criminally charged regarding corruption, resulting in 86 officials being convicted, while a further 296 officials were departmentally charged."
What are conditions like in South African jails?
South Africa's jails were put under the spotlight during the extradition hearing of Shrien Dewani, the Briton who stands accused of ordering a hitman to murder his new wife in 2010.
One of the defense's arguments -- not upheld -- against extradition was that Dewani would not be safe in South African custody.