Afterwards, Ms Cartier and brother Andrew Nisbet were unimpressed by Milner's legal arguments.
"There's just nothing there ... it was a joke. Just another waste of taxpayers' money," Ms Cartier said.
Brother Andrew said she was "clutching at straws ... trying to turn it into something it's not".
He said it was again "very stressful" for the family.
Last December a jury found Milner, 50, guilty of murdering Mr Nisbet in 2009, and guilty of a second charge of attempting to kill him a fortnight earlier.
At the High Court in Christchurch, the Crown proved that Milner had slipped crushed up Phenergan into 47-year old Mr Nisbet's evening meal and killed him.
She then made his death on May 4, 2009 look like suicide in the hope of cashing in a $250,000 life insurance policy.
And the mother-of-two nearly got away with it when police referred the Christchurch delivery driver's death as a suicide to a coroner.
But the Coroner Sue Johnson raised suspicions which prompted police to launch a homicide investigation.
In February, Justice David Gendall sentenced Milner to the statutory life imprisonment and imposed a minimum non-parole period of 17 years.
But Mr Glover today argued there was no way Milner could have crushed up between 14 and 233 Phenergan sedative and anti-histamine pills in delivery driver Mr Nisbet 's food and given it to him without him knowing something was up.
The jury should have been asked to consider how she managed that feat, he said.
Expert defence witness Professor Ian Whyte said it would have required in the region of 45 tablets to achieve level of the drug found in Mr Nisbet's system.
But he accepted it could've been as low as 14.
"I find it very hard to explain that he wouldn't have been aware of it, even if it was just 14 tablets," Mr Glover said.
Justice France pointed to evidence from the police officer who conducted a test showing a meal laced with 25 pills had a slightly bitter taste but "wasn't so bitter that he wouldn't eat it."
Mr Glover said it was far more likely that Mr Nisbet took the fatal overdose himself.
The Crown said there were many strands to the circumstantial case, including forged suicide notes, evidence of Milner's previous attempts to kill him on April 15, 2009, coupled with the "suspicious circumstances" where it was alleged Milner used fake names and addresses to buy Phenergan in the days leading up to the murderous attempts.
Crown lawyer Mark Lillico said it was "scientifically dangerous to take a punt" on how many pills were consumed.
He also reminded the court that Milner's son Adam Kearns gave testimony that he saw his mum crushing up pills and putting them into capsules.
The judges reserved their decision.
Read other stories on the Black Widow trial.
