Ms Seales' legal team has argued that not allowing Ms Seales' doctor to administer lethal medication that would relieve her suffering was contrary to the Human Rights Act.
Dr Andrew Butler said Ms Seales had asserted she was not a vulnerable person, but safeguards were still in place.
"If Lecretia is not in a position to give informed consent, it will not happen."
The Crown argued that there was nothing in current legislation that allowed for doctors to lawfully help to end someone's life and only a change in legislation would make it legal.
Professor Paul Rishworth, QC, said Ms Seales' arguments around who could apply for doctor-assisted death led to a slippery slope and there were details such as the definition of the word terminal that would have to be dealt with. Some patients could live a "very long time" with terminal illnesses, he said.
Human Rights Commission lawyer Matthew Palmer told Justice Collins that if the court found that criminal law was inconsistent with human rights law, then the court did have the jurisdiction to declare that inconsistency, he said.
"Both parties here have raised powerful arguments on either side," Dr Palmer said.
Earlier yesterday, anti-euthanasia group Care Alliance's lawyer Victoria Casey said Oregon legislation, which was being proposed in Ms Seales' case, had no provision for supervising the conditions in which lethal medication was taken and whether it was being taken freely.
In New Zealand there was a documented problem with elder abuse and the results of legalising doctor-assisted deaths could be "chilling", Ms Casey said. She also strongly objected to Ms Seales' lawyers describing physical disability that their client might succumb to as degrading and lacking in dignity with many people suffering the same types of disabilities. The legislation would put those people in danger, she said.
However, Voluntary Euthanasia Society lawyer Kate Davenport, QC, said legalising doctor-assisted death would not open the floodgates for people to be killed. She said the civil case was about Ms Seales and the treatment she was seeking from her doctor.
Her doctor would prescribe medication for the purpose of relieving Ms Seales' suffering, Ms Davenport said.
The decision of when to take the medication would lie with Ms Seales, she said.
Justice Collins reserved his decision.