The page "States Where Holographic Wills Are Legal" from legal zoom lists some 26 united-states states in which holographic wills are valid, plus 9 more that will recognize such wills when they are written elsewhere.
Beyond that, some states consider a holographic will valid for only a limited time, such as one year, after its date. The idea seems to be that a holographic will is supposed to be for emergency situations, when there is no opportunity to have a will drafted and witnessed in the usual way.
Under the common law, holographic wills were valid, if they met a few requirements, such as being entirely in the handwriting of the testator. This satisfied the legal principle that the law "favors testacy over intestacy". But such principles never prevail over specific statutes, and the states that disallow holographic wills have generally done so by statute.
Holographic wills can be harder to prove, cause court contests, and can perhaps be more subject to fraud, or legislators may have thought so. In any event, they have been made invalid in many jurisdictions.
My understanding is that in a state that does not recognize a holographic will, a will not properly witnessed will often be ignored in favor of the legal heirs, that is those who would inherit if there were no will. I am not at all sure about the case where there are no legal heirs, and the state would inherit in the absence of a will. Perhaps there probate judges have more discretion.
I could not find much caselaw or many news reports about holographic wills, and no case where there were no heirs-at-law, and the alternative was for the estate to go to the state (escheat), although some sites mention the possibility. It seems that few cases dealing with holographic wills are not only brought to court, but appealed so that published opinions on them can be found.
The page "New York Holographic Will" (from a law office site) says:
A holographic will is a unique type of will that will only be considered valid if it is made under certain extreme conditions. In all other circumstances, a holographic will will not be valid and will not be probated. If this happens, then your estate will be treated as if you died without leaving a will.
In New York if you do not leave will your estate will be disposed of according to the laws related to intestate succession. NY EPTL § 4-1.1. ... If you die leaving only a holographic will and the court determines it to be invalid, then there is a possibility that your property will end up in the hands of New York state. If you are not survived by any relatives, then your property will escheat to the state.
The page "Handwritten wills can translate into probate problems" says:
In one Arizona case, a partially typed and handwritten document was invalidated. A grandmother’s wishes were tossed aside, and her granddaughter did not share in her legacy.
Ther page "Holographic Will Florida" (From a lawyer's blog) says:
Holographic wills are invalid in Florida and therefore your assets will pass according to the Florida Intestacy Statute. Your assets located in the State of Florida will pass by the Florida Intestacy Statute even if you validly executed your holographic will in another State that allows holographic wills and then you later move to Florida. ... Finally, if there is nobody that applies, meaning you have no family at all, the property will escheat (transfer) to the State of Florida.
The *National Law Reviewe article "Court Holds That Holographic Will Was Not Valid As There Was No Signature" says:
In In the Estate of Hohmann, the decedent died without leaving an executed will, but his caretaker found a hand written document wherein the decedent stated his wishes for his property. No. 04-20-00237-CV, 2020 Tex. App. LEXIS 9216 (Tex. App.—San Antonio November 25, 2020, no pet. history).
The court held that the hand-written document had not been signed and was not valid:
Here, we see no evidence in the written instrument indicating that Raymond intended the phrase “R. Hohmann Estate” to serve as his signature.
In the case Estate of FRANCES BURNS BLACK, Deceased. (L.A. No. 31280. Supreme Court of California. March 1, 1982.) Richardson, J. wrote:
Where, as here, there is no conflict in the evidence, "'the validity of the holographic instrument must be determined entirely by reference to the applicable statutes and principles of law.' [Citations.]" (Estate of Baker (1963) 59 Cal. 2d 680, 683 [31 Cal. Rptr. 33, 381 P.2d 913].) Unanimously in Baker, we stressed that "The policy of the law is toward 'a construction favoring validity, in determining whether a will has been executed in conformity with statutory requirements' [citations]." (Ibid.) Moreover, we affirmed "'the tendency of both the courts and the Legislature ... toward greater liberality in accepting a writing as an holographic will. ...'" (Ibid.) "'Substantial compliance with the statute, and not absolute precision is all that is required. ...'"
In construing section 53 we bear in mind the primary legislative purpose of the holographic will statute which was identified by us in Estate of Dreyfus (1917) 175 Cal. 417, 418-419 [165 P. 941], as the prevention of "fraudulent will-making and disposition of property" by virtue of the recognized difficulty of forging an entire handwritten instrument.
As noted by Professor Osborn: "An extended holograph ... is perhaps the most effective means of proving practical execution, even more than witnesses, and the law relating to holograph wills recognizes this fact. ..." (Osborn, Questioned Documents (2d ed. 1929) p. 682
Our liberal statutory interpretation and emphasis on "substantial compliance" expressed in Baker has been well understood, for there have been few reported decisions subsequent thereto which have adopted the hypertechnical application of section 53 to holographic wills which we disapproved in Baker.
No sound purpose or policy is served by invalidating a holograph where every statutorily required element of the will is concededly expressed in the testatrix' own handwriting and where her testamentary intent is clearly revealed in the words as she wrote them. Frances Black's sole mistake was her superfluous utilization of a small portion of the language of the preprinted form. Nullification of her carefully expressed testamentary purpose because of such error is unnecessary to preserve the sanctity of the statute. Moreover, rejection of the instrument as a will would have the unfortunate practical consequence of passing her estate through the laws of intestacy to the daughter of her predeceased husband by a former marriage -- in fact, a stranger to her -- thereby excluding those whom she described in the holograph as "my very dear friends" and "my adopted family" and the charity which was apparently close to her heart and which she specifically wished to benefit.
In the case of Wilson v. Polite 218 So. 2d 843 (1969) JONES, Justice wrote:
It was alleged in said petition that the said writing was not valid in law as a will, because it did not comply with Section 657 of the Mississippi Code of 1942 Annotated (1956) in that it was not subscribed by the said Clara Thompson. ... The sole question is whether this instrument constitutes a holographic will.
No person has an inherent or constitutional right to make a will disposing of his property. Such is a privilege extended to the citizens by the State. 94 C.J.S. Wills § 3, p. 680 (1956); ... It is a requisite to a valid will that it be executed as prescribed by statute. ...
No matter how earnestly one may desire and intend to make a will, a paper, although fully intended by the writer to be a will, is ineffective and invalid unless its execution meets statutory requirements.
The purpose of statutes prescribing formalities for the execution of wills is not for the purpose of restricting the power of testator to dispose of his property, but it is to guard against mistakes, impositions, undue influences, fraud, deception, etc., which would divert the property of the testator from those intended by him or her to inherit same. The formalities are for the testator's protection also, as well as the beneficiaries'. ...
We have before us here what is claimed to be a holographic will. To be such it must be executed in accordance with the specific requirements of the statute. It must be laid on the table beside the statute to determine whether its execution is in accord therewith. If it is not executed as provided by the statute, it is not a will, regardless of the intention of the alleged testator.
An instrument offered as a holographic will must be a complete and executed document, although absolute precision of execution is not necessary, and all that is required is a clear showing on the face of the instrument of its execution in conformity with the law.
In summary, the court has construed the statute regarding holographic wills to mean (1) it must be signed at the end of a document, testamentary in character, which shows on its face that the testamentary purpose therein expressed is completed, (2) nothing which follows the signature may be considered, (3) if the writing does not meet the requirements of the statute the intent of the writer is immaterial. The part of the document in question which precedes the signatures thereon fails to show on its face that the testamentary purpose was completed. On the contrary the purported signatures appear in the middle of a sentence.
No where is there a court authorized to make a will for any decedent and that is exactly what we would be doing if we said we were going to strike out those words in this instrument which keeps it from being a will.
(There was a strong dissent in this case, which I omit.)