8 CFR § 103.2(b)(8) -

Evidence of eligibility or ineligibility. If the evidence submitted with the benefit request establishes eligibility, USCIS will approve the benefit request, except that in any case in which the applicable statute or regulation makes the approval of a benefit request a matter entrusted to USCIS discretion, USCIS will approve the benefit request only if the evidence of record establishes both eligibility and that the petitioner or applicant warrants a favorable exercise of discretion. If the record evidence establishes ineligibility, the benefit request will be denied on that basis.

ii. Initial evidence. If all required initial evidence is not submitted with the benefit request or does not demonstrate eligibility, USCIS in its discretion may deny the benefit request for lack of initial evidence or for ineligibility or request that the missing initial evidence be submitted within a specified period of time as determined by USCIS.