Artificial feeding vs. Force-feeding
One of the issues which had to be taken up in detail during the revision of the 1991 WMA Declaration of Malta was this difference between "artificial" and "force" feeding.
As mentioned above, force-feeding implies the use of force, of coercion. In the WMA Declaration of Tokyo, (then)[9] article 5 states in fact:
summarized) Art. 5 : Where a prisoner refuses nourishment … unimpaired and rational judgment … voluntary refusal of nourishment, he or she shall not be fed artificially.
The term "artificially" was used at the time, because the main thrust of "Tokyo" was against medical participation in torture, and was not primarily about hunger strikes. However, as mentioned before, when looking into the travaux préparatoires for the WMA Declaration of Tokyo, it is clear that the issue was preventing doctors becoming complicit to torture, in case they were asked to resuscitate prisoners on hunger strike in a situation in which what they were doing was protesting against torture, and refusing to be sent back to torture. It was not the doctors' duty to contribute to sending them back to that same situation of torture. The term "artificial" was perhaps ambiguous, but the whole situation would have been difficult to summarize in the text of a declaration. The situation thus implied could involve either artificial feeding (if the prisoner had passed out during his hunger strike for example) or force feeding, if the prisoner was still conscious enough to struggle against the insertion of any tube. As the WMA Tokyo Declaration meant to not involve doctors in any way, the term artificial feeding was chosen, as it would have seemed obvious that force feeding would be even less justified.
Gastrostomy
Gastrostomy, which is a medical procedure reserved for the alimentation of specific medical patients, and certainly not for hunger strikers, is however foreseen for prisoners who refuse food in specific conditions by the US Federal Bureau of Prisons. The US Department of Justice thus gives clear directives for involuntary medical treatment, and specifically force-feeding of hunger strikers and also mentions gastrostomy as a possibility (for which a "Court order" would be needed…)
See document of the Federal Bureau of Prisons mentioned above in the "References" : P5562.05 of 2005, page 7