I have a couple of interesting issues that are turning out to be impossible to brief:

Does the trial court err in denying a writ of attachment for a witness that both parties agree is too physically ill to bring into court? (assume his testimony is relevant and material)

If witness' testimony would allow for a self-defense instruction, does denial of writ (keeping out evidence that has potential to allow SD instruction) prevent defendant from presenting a complete defense in violation of the 6th Amendment when defendant does not testify?

Was there any reason why the defense could not have requested and conducted a video or audio deposition of the witness? When I was in private practice I used that on occasion fearing my witness would die before trial. If there was an alternative that was available but the defense chose not to use then the trial court had the discretion to deny the writ of attachment.

I agree, but I can't find any authority that supports that argument.

In similar situations I normally rely on "the equitable maxim that a court should not require the doing of a useless thing." Gladewater v. Pike, 727 S.W.2d at 518. Issuance of a writ of attachment would not have accomplished anything as the witness would not have appeared, assuming no peace officer would risk endangering the life of the witness by bringing him forthwith to court.

It is established that the guaranty of compulsory process does not amount to a guaranty of the actual attendance of such witnesses. See 79 P.2d 395 and 60 A.2d 187. The State is required only to make a good faith effort to secure witnesses favorable to the defense. 704 P.2d 944. The right to compulsory process is not absolute or unlimited. 657 S.W.2d 148. It must yield to accomodate other legitimate interests. 483 U.S. 44.

It was not the court's ruling that made the witness unavailable in your case, it was an Act of God. That there were other remedies, including a continuance or a deposition, only demonstrates that the error, if any, was not the cause of any true harm.