Campaigners are set to learn if they have won their High Court battle over the availability of Alzheimer's drugs for people with early-stage disease.
Protesters gathered outside the court during the hearing
The National Institute for Health and Clinical Excellence (NICE) ruled donepezil, rivastigmine and galantamine were not cost-effective in such cases.
But critics argue the decision process was flawed and did not take into account the benefits to carers.
It is the first time a judicial review has been sought on a NICE decision.
Drugs company Eisai brought the case to the High Court with support from fellow drugs firms Pfizer and Shire and the Alzheimer's Society.
During the four-day hearing, which took place in June, lawyers representing Eisai said NICE and its appeal panel failed to assess properly the issues.
They argued that NICE did not properly evaluate the impact of the drugs on the quality of life of carers and that the figures on the cost of long-term care used in their analysis were too low.
In addition, they questioned the accuracy of the test used to determine the severity of a patient's Alzheimer's.
NICE guidance in 2001 recommended the drugs - which can make it easier to carry out everyday tasks - should be used as standard.
But guidance published in November 2006, after months of appeals, stated that the drugs should only be prescribed to people with moderate-stage disease.
NICE said the drugs, which cost about £2.50 a day, did not make enough of a difference to recommend them for all patients and were not good value for money.
Campaigners are angry that people suffering from Alzheimer's have to get worse before they are eligible for treatment.
About 700,000 people in the UK have a form of dementia and more than half of those have Alzheimer's disease.
Neil Hunt, chief executive of the Alzheimer's Society, said: "NICE holds the fate of so many people's lives in its hands, it is only right that its decisions are subject to proper scrutiny.
"Whatever the outcome, we are glad the views of those affected by Alzheimer's disease have finally been heard in court."
Speaking at the launch of the National Dementia Strategy group, Care Services Minister Ivan Lewis said NICE had an incredibly difficult job to do and he was not going to interfere in controversial decisions.
"The point I'd want to stress is, access to medication and drugs is important but it is only a small part of the challenges which are facing families who are struggling with this condition."