Final answer:
The statement from the Heller case demonstrates ethos by showing consistency in the petitioners' historical legal stance and by referencing earlier legal decisions, which adds credibility to the District of Columbia's argument.
Step-by-step explanation:
The transcript provided from the District of Columbia v. Heller case attempts to establish ethos by referencing the legal precedents and arguments previously made by the petitioners in support of their views on gun control. By indicating that the petitioners have consistently argued against the need for a so-called self-defense exception to the firearm functional ban, the speaker reinforces the District of Columbia's longstanding position on this issue, which had also prevailed in the McIntosh v. Washington case. This consistency in legal stance could lend credibility to the District of Columbia's argument, reflecting a principled approach to policy regarding firearms. Additionally, the reference to historic legal decisions showcases an understanding of the legal framework, adding further to the ethos of the statement.