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   STATE OF CONNECTICUT v. BENJAMIN CHASE CARPENTER—
                       CONCURRENCE

   PRESCOTT, J., concurring. Although I agree with the
majority’s conclusion that the defendant cannot prevail
on his claim of instructional error, I reach that conclu-
sion for a different reason. In my view, the defendant’s
claim fails as a matter of law because he failed to brief
adequately how he was harmed by the court’s alleged
failure to give the requested third-party culpability
instruction. Accordingly, I do not reach the merits of
the defendant’s claim on appeal and respectfully concur
in the result.
   ‘‘It is well settled that, absent structural error, the
mere fact that a trial court rendered an improper ruling
does not entitle the party challenging that ruling to
obtain a new trial. An improper ruling must also be
harmful to justify such relief. . . . The harmfulness of
an improper ruling is material irrespective of whether
the ruling is subject to review under an abuse of discre-
tion standard or a plenary review standard. . . . [If]
the ruling at issue is not of constitutional dimensions,
the party challenging the ruling bears the burden of
proving harm.’’ (Internal quotation marks omitted.)
State v. Toro, 172 Conn. App. 810, 816, 162 A.3d 63,
cert. denied, 327 Conn. 905, 170 A.3d 2 (2017).
   This court has held previously that a claim of instruc-
tional error regarding the denial of a third-party culpa-
bility instruction is not of constitutional magnitude. See
State v. Blaine, 168 Conn. App. 505, 516, 147 A.3d 1044
(2016), cert. granted and cause remanded on other
grounds, 325 Conn. 918, 163 A.3d 618 (2017); State v.
Inglis, 151 Conn. App. 283, 296–97, 94 A.3d 1204, cert.
denied, 314 Conn. 920, 100 A.3d 851 (2014), cert. denied,
     U.S.     , 135 S. Ct. 1559, 191 L. Ed. 2d 647 (2015).
Accordingly, ‘‘the defendant has the appellate burden
to establish harm flowing from the [instructional] error,
in order to secure a reversal of the judgment.’’ (Internal
quotation marks omitted.) State v. Malave, 250 Conn.
722, 741, 737 A.2d 442 (1999), cert. denied, 528 U.S.
1170, 120 S. Ct. 1195, 145 L. Ed. 2d 1099 (2000); see
also State v. Arroyo, 284 Conn. 597, 614–615, 935 A.2d
975 (2007) (engaging in harmful error analysis after
determining court improperly refused to give third-
party culpability instruction).
  In the present case, the defendant’s principal brief
contains no analysis of whether the court’s failure to
give the requested third-party culpability instruction
was harmful under the circumstances of this case. That
brief fails to discuss the appellant’s burden in this regard
or to analyze any of the factors that courts typically
employ to assess whether the defendant has met his
burden to demonstrate harm. See, e.g., State v. Arroyo,
supra, 284 Conn. 614–15; State v. Blaine, supra, 168
Conn. App. 516–17.
   Rather, the defendant presents his harmful error anal-
ysis for the first time in his reply brief in response to
the state’s argument that any instructional error was
harmless. As we have indicated on numerous occasions,
we will not consider arguments raised for the first time
in a reply brief. See, e.g., State v. Toro, supra, 172 Conn.
App. 820. Because the defendant failed to address the
issue of harm in his principal brief, he cannot meet his
burden of establishing harmful error. Thus, even if the
defendant were able to demonstrate that he was entitled
to a third-party culpability instruction, he would not be
entitled to the relief he seeks, namely, a reversal of the
judgment and a new trial. Accordingly, I would affirm
the judgment of the court without reaching the merits
of the defendant’s claim of instructional error.
