the liberatarian's dilemma

I have problems with this:

After her oncologist prescribed a cancer drug that would cost $4,000 a
month, the newspaper reported, "Wagner was notified that the Oregon Health
Plan
wouldn't cover the treatment, but that it would cover palliative,
or
comfort,
care, including, if she chose, doctor-assisted suicide."

Now, in theory, I support Oregon's assisted suicide law, like to good little liberatarian I am. "What right does the government have to decide whether a rational adult wants to take his or her life?" I ask.

But here's the thing- there is always someone who has an interest in gradma kicking the bucket- whether it's the beneficiaries of her estate, or the government who's footing the medical bills, or the family who just doesn't want to be bothered with it all.

I usually try to solve these problems by trying to weigh the negative impact on freedom against the negative impact to society by allowing the activity. I'm coming up with a blank here- I just don't know. Any thoughts?