Why did special legislation have to be passed for Scipio Africanus the Younger's second consulship?

Special legislation was required for Scipio Africanus the Younger's second consulship in 134 BCE because, by that time, Roman law had been updated to prohibit individuals from holding a second consulship.12

During the 2nd century BCE, the Roman Republic implemented various regulations to govern the cursus honorum, or the sequence of political offices, to curb the intense electoral competition among senatorial families. These reforms included setting minimum age requirements, mandating a two-year interval between offices, and eventually banning the iteration of the consulship entirely.1

Despite these prohibitions, Scipio was elected to a second term to take command of the war against the Celtiberians in Spain, where Rome had suffered a series of humiliating setbacks. His election and the subsequent need for a legal exemption highlighted a growing trend of circumventing established constitutional regulations by appealing directly to popular assemblies, a practice that contributed to the political volatility of the late Republic.21