Brief of the National Association of Criminal Defense Lawyers, National Association of Federal Defenders, National Association for Public Defense, National Immigration Project of the National Lawyers Guild, and Immigrant Defense Project, As Amici Curiae in Support of Petitioner.

Argument: The Board of Immigration Appeals' (BIA) interpretation of "aggravated felony" deserves no deference. Section 1101(a)(43) has extensive criminal applications, with substantial penal consequences. Because section 1101(a)(43) has criminal law consequences, the rule of lenity applies and the BIA is owed no deference. Respect for separation of powers, an absence of agency expertise, and the need for consistency all independently militate against deference. Even if Chevron deference applied here, the outcome would be the same. The manner in which the BIA interpreted the provision was unreasonable. Empirical evidence confirms that Congress intended the interstate commerce element to function substantively.

Brief of the National Association of Criminal Defense Lawyers as Amicus Curiae in Support of Petitioner.

Argument: BIA interpretations of "aggravated felony" do not qualify for Chevrondeference. Section 1101 (a)(43) has extensive criminal applications, with substantial penal consequences. Because Section 1101 (a)(43) has extensive criminal consequences, the Rule of Lenity rather than Chevron must be applied to resolve statutory ambiguities.  This Court's precedent dictates that the rule of lenity applies, requiring "aggravated felony" to be construed narrowly and in favor of petitioner. Applying the rule of lenity rather than Chevron to statutes with both civil and criminal applications fulfills the rule's purposes and protects core constitutional values. Babbitt's footnote does not command a contrary result. Even if the Chevron framework applies, deference to the BIA's interpretation is not warranted here. The BIA does not administer criminal laws and lacks relevant criminal law expertise. Affording Chevron deference to the BIA's interpretation would create significant practical difficulties for criminal defense lawyers and their clients.