Day v. McDonough, 547 U.S. 198 (2006), is a US Supreme Court case involving the one-year statute of limitations for filing habeas corpus petitions that was established by the Antiterrorism and Effective Death Penalty Act of 1996 (AEDPA). In a 5–4 decision, the Court ruled that if the government unintentionally failed to object to the filing of a petition after the AEDPA limitations period has expired, it is not an abuse of discretion for a district court to dismiss sua sponte (on its own initiative) the petition on that basis. Background On September 3, 1998, Patrick Day was convicted of second-degree murder in Florida state court and sentenced to imprisonment for 55 years. After the Florida First District Court of Appeals affirmed Day's conviction and sentence, the Antiterrorism and Effective Death Penalty Act (AEDPA) 365-day statute of limitations for Day to obtain federal habeas corpus relief began to run on March 20, 2000. On March 9, 2001, Day filed a post-conviction petition under Florida state procedure, which tolled the limitation period for filing a habeas petition until December 3, 2002, when the First District Court of Appeals issued its mandate denying Day collateral relief. By then, Day had used 353 of his allotted 365 days and accordingly had until December 16, 2002 to file a federal habeas petition. However, Day did not file his petition until January 8, 2003, after the limitations period had run. A US magistrate judge nevertheless acknowledged that the petition was "in proper form" and ordered Florida to file an answer and to make all arguments regarding Day's potential failure to exhaust state remedies or procedural default. The order stated that those arguments would be waived if not addressed in the answer, but it did not expressly mention the statute of limitations. The answer of the State of Florida erroneously asserted that Day's petition was timely filed after "352 days of untolled time" and then addressed Day's substantive arguments. In December 2003, the court sua sponte issued an order to show cause why Day's petition should not be dismissed as untimely. Day made three arguments against dismissal. Firstly, Day argued that the court should not dismiss his complaint after it had been pending for nearly a year without any suggestion that it was untimely. Secondly, Day argued that he had 90 days from the denial of his motion for rehearing on collateral appeal to file a