13 considering his claim, we "rarely exercise[]" this power and only do so in instances where a "serious and obvious" mistake poses a "substantial risk of a miscarriage of justice." Commonwealth v. Oakes, 407 Mass. 92, 94-95 (1990). Second, the challenge fails because the statute is neither overbroad nor vague. William bears the burden of showing "'from the text of [the law] and from actual fact' . . . that substantial overbreadth exists" (citation omitted). Hicks, 539 U.S. 113, 122 (2003). Virginia v. As an initial matter, § 43A (a) is a statute directed at a course of conduct, rather than speech, "and the conduct it proscribes is 'not necessarily associated with speech'" (citation omitted). United States v. Petrovic, 701 F.3d 849, 856 (8th Cir. 2012) (considering similar statute). In particular, § 43A (a) specifically criminalizes "a knowing pattern of conduct or series of acts . . . directed at a specific person, which seriously alarms that person and would cause a reasonable person to suffer substantial emotional distress" (emphases added). As the United States Court of Appeals for the Ninth Circuit held in United States v. Osinger, 753 F.3d 939, 944 (9th Cir. 2014), when considering a similar statute, because § 43A (a) "proscribes harassing and intimidating conduct, the statute is not facially invalid under the First Amendment."