On March 13, 1964 in Queens, New York, Catherine Genovese was entering her apartment when she was stabbed twice by a man. She screamed for help saying, “Oh, my God! He stabbed me! Help me!” and collapsed. Genovese continued to scream for help while her assailant stabbed her to death. As she lay dying, the assailant raped her and stole $50.00 from her wallet. Over twelve people, mostly neighbors of Genovese, heard her screams, but chose to do nothing. For various reasons, such as they did not want to get involved, or thinking that it was just a lover’s brawl, nobody picked up the phone to call the police. Some people even thought that since the screams were so loud, someone else would surely call.  This is one of the most illustrative cases of the Bystander Effect.
A psychology glossary online defines the Bystander Effect as:
The Bystander Effect is a social phenomenon in which a person (or persons) are less likely to offer help to another person (or persons) when there are more people around who can also provide assistance. […] Thus, when in a group, people are less likely to offer help than when they are alone. 
Although counterintuitive, it is quite common in sexual assault cases.
For example, in the 2012 Guwahati Molestation case, a girl was molested by over twenty men in a gang in a very crowded street while onlookers failed to intervene. 
In a more recent case, on February 8, 2014, a fourteen year-old girl from Manipur went outside to the Munirika market in New Delhi to purchase dish washing liquid. She was at a pharmacy shop when a man saw her and dragged her away.  The man used some negative language towards her pertaining to her Northeastern features, and then dragged her away as she started screaming for help from the shopkeepers. There were pharmacy owners and general store owners who heard her scream for help, but no one intervened. The pharmacy owner in fact chose to close the shop and go home. The assailant ultimately physically abused her and raped her for several hours in his house located close to the pharmacy shop. She was only able to escape several hours later when he went to the bathroom. While the police caught the main perpetrator several hours later, they also arrested the pharmacy owner who chose to do nothing. He was later released on bail. The other owners were not charged.
Generally, under common law, a bystander cannot be held responsible unless the bystander created the dangerous situation or has a special relationship with the victim, i.e., common carriers, or employers. However, under the 2012 Protection of Children from Sexual Assault Act (POCSO), under Section 19, “any person . . . who has apprehension that an offence under this Act has been committed or has knowledge that such an offence has been committed, he shall provide such information to the a) the special juvenile police unit b) the local police.” Failure to do this can get that person imprisonment that may extend to six months, or with fine, or with both. Using this section, bystanders under POCSO can and have been charged.
It is debatable whether bystanders should be held accountable for the actions of others. In the Steubenville rape case, images of the sexual assault were passed around online by several individuals in that high school. Should they all be charged? Though these actions may seem harmless, some actions by bystanders are not without consequences and have resulted in deadly results for victims and their families. For example, Rehtaeh Parsons and Audrie Pott both committed suicide after images of their sexual assault were passed among their peers.  The defense from many bystanders in the above scenarios was that they thought the act was consensual and did not feel that it was a crime.
To combat this phenomenon, organizations such as Rape Abuse and Incest National Network (RAINN) advocate for Bystander Intervention where bystanders are encouraged to engage in a) direct intervention, b) delegating an intervention, or c) creating a distraction. While direct intervention seems to be the most common answer, delegating an intervention is also equally effective. One can do that by simply talking to one of the friends of the individuals involved, or speaking to other figures of authority such as police officer or a security officer. Lastly, distraction works as well where the bystander simply creates a distraction by asking a question from one of the individuals involved that helps to remove that person from the situation temporarily.
Lastly, many people choose not to intervene because they personally do not want to held liable. To combat this issue, many states have passed Good Samaritan laws that does not hold the person personally liable if they are engaging in good faith to help others, unless they created the peril for the victim in the first place.
 “The Bystander Effect: Death of Kitty Genovese.” Alleydog.com. Social Psychology Videos, n.d. https://www.alleydog.com/video/social-psychology/bystander-effect-death-of-kitty-genovese.php
 “Bystander Effect.” Alleydog.com. Online Glossary, n.d. http://www.alleydog.com/glossary/definition-cit.php?term=Bystander Effect
 Sahni, Diksha and Preetika Rana. “Guwahati Molestation: ‘What Has Happened to Our Society?'” The Wall Street Journal, 13 July 2012. https://blogs.wsj.com/indiarealtime/2012/07/13/guwahati-molestation-what-has-happened-to-our-society/
 PTI. “Manipur Girl Raped in South Delhi, Protests by NE Students.” Times of India, 8 Feb 2014. http://timesofindia.indiatimes.com/city/delhi/Manipuri-girl-raped-in-south-Delhi-protests-by-NE-students/articleshow/30065854.cms
 Culp-Ressler, Tara. “Why People Don’t Intervene When They Witness a Sexual Assault, and How We Can Change That.” Think Progress, 21 Oct 2013. https://thinkprogress.org/why-people-dont-intervene-when-they-witness-a-sexual-assault-and-how-we-can-change-that-2d587f405059