Sterile veterinary Nembutal as it has been sold in Thailand
Nembutal continues to be sold over-the-counter (lawful) and over the Internet (check your local laws regarding legality) from several countries around the world.
However, while the purchase of Nembutal might be quick and legal in some countries, the importation of Nembutal to your home country is almost certainly illegal and may attract penalties. You are strongly advised to check the particular laws of the jurisdiction in which you reside before going further.
That said, if a seriously ill person purchases Nembutal lawfully in one country and then takes the drug and ends their life in that country, no laws will likely be broken.