What is the reson behind Emergency in INDIA in 1975-1977? ???

From the early 1970s , wide-spread discontent shook India: large sections of the population came out in demonstrations against rising prises, fall in the supply of essential commodities, unemployment, and more importantly, corruption in government administration. These protests reached a crescendo in two states – Gujarat and Bihar – in 1974, with students leading the agitations and giving them an organized shape. The Gujarat state government ruled by Indira Gandhi’s Congress Party was forced to resign that year. In fresh elections to the Gujarat legislature in early June, 1975, the Congress was trounced and the opposition parties formed the new government in that state. Indira realized that she was losing her grip, and was threatened by a political crisis. The threat became imminent when on June 12, 1975, the Allahabad high court of the state of Uttar Pradesh (from where Indira Gandhi won in the parliamentary election in 1971), declared her election invalid on two corruption charges in the conduct of her poll campaign at that time. She was accused of violating the Indian law by first, using an officer of her government to make campaign arrangements, and secondly, by using other state officers to put up speaker’s stands in her constituency and supply electricity to her amplifying equipment. The high court judgment debarred her from holding the office of prime minister, but granted a stay of the order for 20 days – to allow her party to choose another leader (since the Congress party still enjoyed a majority in the Indian parliament).
The era of Emergency, which was inaugurated by Indira Gandhi on June 25/26, 1975, was the darkest chapter in the democratic history of India (1991 to 2000 A D is the darkest economic decade). 
The invalidation of the Prime Minister's selection by the Allahabad High Court, is the `causa causans' of the mid-night proclamation of Emergency.