MEXICO CITY, Jan 2 (Reuters) - Mexico's Supreme Court on Monday elected its first female president, who has pushed back against the government's nationalist energy agenda, amid a succession process clouded by allegations of plagiarism against another justice competing for the job.Pina has defended Mexico's transition to renewable energy, setting her against parts of a contentious electricity law championed by President Andres Manuel Lopez Obrador that favors the country's state-run, fossil-fuel dependent energy firms.She takes over from Arturo Zaldivar amid a charged debate about who should lead the court fueled by a December media report alleging that another contender for the top job, Justice Yasmin Esquivel, had plagiarized her undergraduate thesis.Lopez Obrador, who nominated Esquivel to sit on the 11-member court in 2019, had blasted the plagiarism report by media outlet Latinus as an attempt to discredit the government and what he calls his transformation of Mexico.The president has pressured the court to back his policies, in particular his drive to give control of the energy sector to national power utility Comision Nacional de Electricidad (CFE) and state oil firm Petroleos Mexicanos (Pemex)."