Houston billionaire Robert Brockman, the defendant in the United States’ largest-ever tax evasion case, was hospitalized for five days in March, according to a court filing unsealed Wednesday. The 79-year-old former CEO of Reynolds & Reynolds is charged with squirreling away some $2 billion in assets and income and illegally concealing the money from the federal government in offshore accounts. His lawyers say he is mentally incapacitated, a claim prosecutors contest. On March 14, the day he was admitted for treatment, he had been undergoing neurological tests related to the case. The cause of his hospitalization was redacted from the filing. The defense has asked the court to delay the deadline for attestations to his mental competency, currently set for August, by 45 days.