In a 35-page filing aimed at public opinion as much as the judge, Justice Department lawyers questioned Apple’s motivation for defying U.S. Magistrate Judge Sheri Pym’s order this week to help the FBI open Syed Rizwan Farook’s encrypted iPhone 5c.

The government argued Friday that Apple Chief Executive Tim Cook’s public Feb. 16 letter declaring, “We oppose this order,” should be taken as the company’s response.

Apple’s refusal, they wrote, “appears to be based on its concern for its business model and public brand marketing strategy,” not a legal rationale.

Apple technicians told investigators they could write the software the FBI wants to unlock Farook’s phone, and technology providers previously have written code to comply with subpoenas and court orders, according to the filing.