A special Central Bureau of Investigation court on December 22, 2017, acquitted all the accused -- including former telecom minister A Raja, Essar promoters Ravi Ruia and Anshuman Ruia and former bureaucrats -- in the 2G telecom spectrum allocation case, saying the special public prosecutor "miserably failed" to prove any charges against the accused.
Here's a look at a few high-profile cases in which question marks were raised by various courts over the CBI's probe.
Aircel-Maxis 2G case
August 2014
CBI files chargesheet against former telecommunications minister Dayanidhi Maran and his brother Kalanithi Maran and several others for allegedly influencing Aircel to sell its company to Maxis
February 2017
CBI special court drops all charges, saying CBI pressed charges due to misreading of official files
Hindalco coal block
October 2013
CBI files FIRs against Aditya Birla group chairman K M Birla and former coal secretary P C Parakh for criminal conspiracy and misconduct
September-November 2013
Special court pulls up CBI for closing case in a hurry; directs agency to record former PM Manmohan Singh's statement
September 2015
SC asks CBI for further probe
Other coal allocations
CBI investigates 33 coal allocation irregularities between 2006 and 2009, of which final reports are filed in 28 cases. A special court pulls up the CBI for shoddy investigations in various cases, including the ones involving Rajya Sabha MP Vijay Darda and former coal secretary H C Gupta that were re-opened by the investigating agency
Bofors scandal
October 1999-2000
CBI files chargesheet against Hinduja brothers, former defence secretary S K Bhatnagar and AB Bofors for criminal conspiracy, cheating, forgery under Indian Penal Code and other provisions
May-October 2005
Delhi high court quashes charges against Hinduja brothers -- Srichand, Gopichand and Prakashchand -- and Bofors. A special court later reprimands CBI for causing exchequer loss of around Rs 250 crore in the case
Aarushi murder case
April-October 2013
CBI tells special court that Rajesh and Nupur Talwar killed their daughter Aarushi and domestic help Hemraj in May 2008
October 2017
Allahabad HC acquits Rajesh and Nupur Talwar, saying they could not be held guilty based on evidences presented
Bellary illegal mining
October 2012
CBI files chargesheet against former Karnataka chief minister B S Yeddyurappa and others for alleged abuse of position and involving bribery of Rs 40 crore
October 2016
CBI special court acquits Yeddyurappa, 13 others, stating the prosecution failed to establish their guilt
