American Airlines and US Airways are pushing back hard against the U.S. Department of Justice, filing court papers blasting the government’s bid to block their pending $11 billion merger.

Answers to complaints are usually brief, dry affairs, filled with sentences like “Defendant denies the allegations in paragraph 39.” Not so with American and US Airways, which to date have taken a best-defense-is-a-strong-offense strategy in litigating the case.