In 1969 he entered the Southeast Asia Program graduate program at Cornell University, where his thesis on the end of Thailand's absolute monarchy and transition to a constitutional monarchy was supervised by David K. Wyatt. While at Cornell Batson attracted the attention of Walter LaFeber, the eminent historian of American foreign policy, whom he served under as a teaching assistant. Sifting through neglected files at the National Archives in Bangkok, Batson uncovered a long lost collection of papers in which the concept of democracy in Thailand was debated between the seventh Bangkok king and his ministers and advisers. He translated a selection of these and published them as Siam's Political Future: Documents from the End of the Absolute Monarchy in 1974. He was a research fellow at the Australian National University in the late 1970s, during which time he revised his dissertation for publication as The End of the Absolute Monarchy in Siam by the Oxford University Press in 1984. He wrote a work on the Thai literary figure and political activist, Kulap Saipradit. He also began studying Japanese-Thai relations with Shimizu Hajime inspired Southeast Asia under Japanese Occupation and The Tragedy of Wanit: A Japanese Account of Wartime Thai Politics in 1980 and 1990, respectively.