Bahujan Samaj Party (BSP) chief Mayawati on Wednesday said the NDA government at the Centre should learn "its lessons on Constitution at the earliest".The former Uttar Pradesh Chief Minister said the Supreme Court ruling restoring the ousted Congress government in Arunachal Pradesh was an apt moment for the Modi government to embrace constitutional propriety."In the case of Arunachal as well as Uttarakhand crisis, it was evident that the NDA government was not working as per the constitution," she said in a statement.She alleged that in Arunachal, the Raj Bhawan had become a hub to trigger dissent for the then ruling party there.