There is ultimately no meaningful regulation of name choice in the United States, but failing to follow convention can be a pain.
Many countries have far more rigorous regulation of names and often require that a name be on a pre-approved list or at least that it receive advanced governmental approval.
For example, I changed my surname when I married from "Willeke" to "Oh-Willeke" but many private and governmental computer systems do not accept hyphens in names. Non-standard characters and different kinds of punctuation pose similar issues. For example, most databases cannot handle Greek/Cyrillic alphabet characters such as "π" so they would have to spelled out "Pi" for inclusion in many databases.
For example, I am not certain that the databases of most government agencies, even in Colorado which has a large Hispanic population, are capable of distinguishing between ñ and n. Similarly, I am sure that "Æ" (the AE grapheme) would be recorded as "ae" in most computerized databases and on most identification documents. Likewise, few identification document systems or computer databases can process Korean Hangul characters, so my children's middle names are in a particular romanization of the true and correct Hangul spelling of those names.
Various agencies such as vital statistics departments and driver's license bureaus have practical limitations on their ability to input information into computer systems, but that doesn't really limit a true name, which at common law could be changed without resort to the court system or any bureaucracy, something which remains the law in Colorado.
The bottom line is that even if your name in its true form has a representation in symbols that a database can't process and that really and truly is recognized in the law as your legal name, as a matter of practical reality, many entities that deal with names will be limited to a romanization of those names.
Consider the following excerpt from a court of appeals case in Colorado that explains the underlying law:
Walter Knight, an inmate of the State Prison, petitioned the district
court to change his name to Sundiata Simba. His reasons were 'to
acknowledge the heritage of (his) past, and to Fortify (his)
acceptance of (his) religious beliefs as required by (his) faith.'
Nine months later, the request was denied. We reverse.
The statute under which the petition was filed, § 13--15--101,
C.R.S.1973, provides that the court must approve the change of name if
it is 'satisfied that the desired change would be proper, and not
detrimental to the interests of any other person.' Here, the court
held that the change would not be 'proper' because Knight has a
lengthy criminal record, is incarcerated, and an F.B.I. 'rap' sheet is
extant which lists him under his present name. However, there was no
evidence Before the court as to how the name change would be
prejudicial to prison or police authorities. Therefore, we do not
consider any of these reasons, without additional proof, as sufficient
basis for the court to conclude that the change of name would be
improper. In this day when a Lew Alcindor elects to be known as Kareem
Abdul-Jabbar, and Cassius Clay opts for Muhammad Ali, the desire of
Walter Knight to reflect his African heritage by adopting the [36
Colo.App. 189] name Sundiata Simba should not be dismissed lightly.
Cf. Petition of Rusconi, 341 Mass. 167, 167 N.E.2d 847.
At common law, a person could adopt another name at will. Statutes
setting forth procedures to be followed in changing a name merely
provide an additional method for making the change. See 57 Am.Jur.2d
Name §§ 10 and 11. It is more advantageous to the state to have the
statutory method of changing names followed, Application of McGehee,
147 Cal.App.2d 25, 304 P.2d 167, and for that reason applications
under the statute should be encouraged, Petition of Buyarsky, 322
Mass. 335, 77 N.E.2d 216, and generally should be granted unless made
for a wrongful or fraudulent purpose. Application of Ferris, 178 Misc.
534, 34 N.Y.S.2d 909. See generally Annot., 110 A.L.R. 219.
While a court has wide discretion in matters of this type, it should
not deny the application for a change of name as being improper unless
special circumstances or facts are found to exist. Included in these
would be 'unworthy motive, the possibility of fraud on the public, or
the choice of a name that is bizarre, unduly lengthy, ridiculous or
offensive to common decency and good taste.' In re M., 91 N.J.Super.
296, 219 A.2d 906; See Petition of Rusconi, supra. Likewise, there is
authority to deny the change if the interests of a wife or child of
the applicant would be adversely affected thereby. See Annot., 53
We do not suggest that a court must grant every petition for change of
name; rather, we hold that some substantial reason must exist for
denying such petition, and that none appears in the record Before us.
See In Re Ross, 8 Cal.2d 608, 67 P.2d 94. Before a court denies a
request for a change of name under the statute, it should conduct an
evidentiary hearing to determine if good and sufficient cause exists
to deny the application. Cf. Henderson v. Industrial Commission,
Colo.App., 529 P.2d 651.
In re Knight, 36 Colo.App. 187, 188-189, 537 P.2d 1085, 1086 (1975). See also In re Cruchelow, 926 P.2d 833, 834 (Utah 1996) (at common law an individual had a right to change his or her name at will); In re Porter, 31 P.3d 519 (Utah 2001) (it was an abuse of discretion to deny someone's request to change his name to Santa Claus); In re Mokiligon, 106 P.3d 584 (N.M.App. 2004) (summarily reversing a trial court's refusal to allow a name change from "Snaphappy Fishsuit Mokiligon" to "Variable").
In 2008, when the Colorado DMV prohibited newlywed women from changing their middle names to their maiden name and then adopting the surname of their spouses, this regulation caused such an outcry that it was promptly dropped at the insistence of the Governor, but the state DMV still requires court recognition for more significant name changes.
The offending rule is found in the Colorado Code of Regulations at 1
CCR 204-13 Part 2.3.5, and relies on Colorado Revised Statutes §
42-2-107(2) and § 42-2-302(2), C.R.S., for authority. But, neither
statute actually purports to limit the means by which someone may
change their name in Colorado. They simply require that your state ID
or driver's license have your name on it.
The replacement rule, which is still far more rigid than the case law which recognized a common law right to change your name at any time with or without a court application to do so stated:
2.3.5 A certified certificate of marriage, decree of dissolution of marriage or legal separation issued by any Native American Tribal
court or an authorized government agency or court of the United
States, any territory, or state of the United States, or any of their
political subdivisions, or any court-ordered name change entered by
any state or federal court may be used to modify the full legal name
of the applicant.
188.8.131.52 Name change as a result of marriage shall be subject to the following conventions:
(1) the existing last name is replaced with the spouse’s last name;
(2) the existing last name is added as a second middle name and the
spouse’s last name becomes the applicant’s last name;
(3) the existing last name replaces the existing middle name and the
spouse’s last name becomes the applicant’s last name;
(4) the spouse’s last name replaces the existing middle name and the
existing last name remains the applicant’s last name;
(5) the spouse’s last name is added before or after the existing last
name via a hyphen or space and becomes the applicant’s last name.
184.108.40.206 All non-court-ordered name changes will require completion, and submission to the department, of the Affidavit of Name Change
for a Colorado driver’s license or identification card, form DR-2203.