Is there an obligation to equalize the sentence of co-defendant?

Generally, there is no obligation to equalize the sentences of co-defendants, as long as the disparity is not "unwarranted." United States v. Shabani, 48 F.3d 401, 404 (9th Cir.1995). The transcript of Montoya's sentencing hearing reveals that the government decided not to pursue its argument that the ledgers should be used to calculate Montoya's sentence. Apparently, the government didn't feel it had carried its burden of proving Montoya's connection with the 459 kilograms of cocaine listed in the ledgers.