I would like to start with the four plant limit. Truthfully I don't think there should be a limit and that cannabis should just be completely decriminalized but I understand that that won't  happen anytime soon due to the number of people who would abuse the whole system. Since there is going be a limit,  I think the number of plants allowed should be significantly increased and broken down into stages(x number of plants in flower[more than 4], x number in veg, and x number seedling/cloning). The current 4 plant limit doesn't usually last a medical user from one harvest to the next. This is due to the length of time it takes to properly grow a cannabis plant. For reference and my experience, a grow is going to take you 60+ days from seed to end of veg stage, then you are looking at 60 to 100+ days in flower stage, next you have 14 to 21 days for a slow dry and finally a minimum of 21 days curing. In total you are looking at 6 months from seed to usable product and unless you are an amazing grower those four plants are not going to produce enough flower to last an additional 6 months for the next grow to be ready.

Then to throw a whole different issue in to the 4 plant limit is male plants. Most regular seeds you have a 50/50 ratio of male to female. I'm sure you are aware that male plants do not produce flower, so is out of those four seeds you planted 2 turn out to be males you'll only have to flower producing plants and half of the amount of flower you though you would have had lasting even less time. And before someone tell you they can just start two more, that is not possible for everyone as it would require a different grow area and grow light unless you are growing autoflowering plants. Photo period plants require a certain number of hours for veg stage and a different number of hours for flower. So growing said new seedlings with flowering plants and there light schedule the seedlings are going to try to go strait into flower and are going to grow properly. 

I guess I should include that I do not partake in cannabis myself but to I grow and provide for my end stage wife. Cannabis is the only thing that provides her with relief from the side affects of her treatments and prescription medications. I am sure if there were more people on your board that had to sit and hold there significant other as they are suffering from pain, nausea, sickness, days without sleep, ect. knowing there is nothing else you can do for them. That you wouldn't be binding the hands of those in Va that are looking to help themselves or family members.