1. Core Legal Answer & Context: This scenario involves criminal liability under the Indian Penal Code (IPC) for gang rape, common intention, criminal conspiracy, and abetment. The core principle is that when multiple individuals act with a shared criminal objective, their individual actions contribute to a collective liability.

2. Relevant Statutes and Sections:

• Indian Penal Code, 1860, Section 34 (Acts done by several persons in furtherance of common intention): "When a criminal act is done by several persons in furtherance of the common intention of all, each of such persons is liable for that act in the same manner as if it were done by him alone."
• Indian Penal Code, 1860, Section 120A (Definition of criminal conspiracy) & 120B (Punishment of criminal conspiracy): An agreement between two or more persons to do an illegal act, or to do an act which is not illegal by illegal means.
• Indian Penal Code, 1860, Section 376D (Gang rape): "Where a woman is raped by one or more persons constituting a group or acting in furtherance of a common intention, each of the persons constituting such group or acting in furtherance of such common intention shall be deemed to have committed the offence of gang rape."
• Indian Penal Code, 1860, Section 107 (Abetment of a thing): Defines abetment as instigating, engaging in conspiracy, or intentionally aiding.
• Indian Penal Code, 1860, Section 109 (Punishment of abetment if the act abetted is committed in consequence and where no express provision is made for its punishment): If the act is committed in consequence of the abetment, and there is no specific punishment for the abetment, the abettor is punished with the punishment provided for the offence.

3. Important Landmark Cases:

• Mahbub Shah v. Emperor (AIR 1947 PC 118): This Privy Council case is a landmark for Section 34 IPC, emphasizing that 'common intention' requires a pre-arranged plan and a meeting of minds, which can develop on the spot. All participants in the common intention are liable for the criminal act.
• Pandurang v. State of Hyderabad (AIR 1957 SC 216): The Supreme Court reiterated that Section 34 creates no distinct offence but lays down a rule of evidence. It requires a common intention and participation in the criminal act. Mere presence is not enough; there must be active participation or presence coupled with common intention.

4. Clear Conclusion: Based on the principles of common intention, criminal conspiracy, and abetment:

(i) Those who were members of the plan but did not participate in the rape:

• Criminal Conspiracy (Section 120B IPC): Since they decided to act in concert with a common intention to commit rape, they are liable for criminal conspiracy to commit rape, irrespective of their direct participation in the act itself. The agreement itself constitutes the offence.
• Common Intention (Section 34 IPC) / Gang Rape (Section 376D IPC): If their non-participation was merely due to circumstances or they were present and ready to assist, they could still be held liable for gang rape under Section 376D read with Section 34 IPC, as long as the rape was committed in furtherance of the common intention they shared. However, if they merely planned and then completely withdrew without any further action or presence, their primary liability would be for conspiracy.

(ii) Those who committed the rape:

• Gang Rape (Section 376D IPC) read with Section 34 IPC: These individuals are directly liable for the offence of gang rape. Since more than one person committed the rape in furtherance of a common intention, each of them is deemed to have committed the offence of gang rape. Their direct involvement, coupled with the pre-arranged plan and common intention, makes them principal offenders.

(iii) The sole lady member who fully facilitated the rape:

• Abetment (Section 107 read with Section 109 IPC): By 'fully facilitating' the commission of rape, she is liable as an abettor. Facilitation falls under 'aiding' the commission of the act. Since the rape was committed in consequence of her abetment, she would be punished for the offence of rape itself, as per Section 109 IPC. Her liability would be the same as if she had committed the rape herself, even if she did not physically participate in the sexual act.
• Common Intention (Section 34 IPC) / Gang Rape (Section 376D IPC): Given her active role in 'facilitating' the rape as part of a group acting in furtherance of a common intention, she could also be held liable for gang rape under Section 376D read with Section 34 IPC, as her facilitation is an act done in furtherance of the common intention. The term 'facilitated' strongly suggests active participation in the overall criminal act, pre-arranged criminal act.