Decentralized planning, which involves shifting decision-making power and resource allocation from central authorities to local bodies, is widely advocated as a powerful tool for enhancing both economic development and social justice. The premise is that local communities are best positioned to understand their own needs and priorities.

Enhancing Economic Development:

1. Tailored Solutions: Local communities have a better understanding of their specific resources, challenges, and opportunities. Decentralized planning allows for the formulation of development plans that are tailored to local conditions, leading to more effective and sustainable economic projects (e.g., appropriate infrastructure, skill development programs relevant to local industries).
2. Efficient Resource Utilization: Local bodies can identify and prioritize projects that yield the highest returns for their specific context, minimizing wastage of resources on centrally imposed, ill-fitting schemes. This leads to more efficient allocation and utilization of funds.
3. Mobilization of Local Resources: Decentralization encourages local resource mobilization, both financial (through local taxes, community contributions) and human (through voluntary labor, local expertise), fostering a sense of ownership and self-reliance.
4. Innovation and Experimentation: Local governance provides a fertile ground for innovation and experimentation in development strategies. Successful local models can then be scaled up or adapted elsewhere.
5. Reduced Bureaucratic Delays: By bringing decision-making closer to the ground, decentralized planning can reduce bureaucratic red tape and delays often associated with centralized systems, speeding up project implementation.

Promoting Social Justice:

1. Inclusivity and Participation: Decentralized planning mechanisms, such as Gram Sabhas (village assemblies) in India, provide platforms for direct participation of citizens, including marginalized groups (women, Scheduled Castes, Scheduled Tribes). This ensures that their voices are heard, and their needs are incorporated into development plans, making the process more inclusive.
2. Targeted Interventions: Local bodies can identify specific pockets of poverty, social exclusion, or deprivation within their jurisdiction more accurately than a distant central authority. This allows for the design and implementation of targeted interventions that directly address inequalities and uplift vulnerable sections.
3. Accountability and Transparency: When decisions are made locally, accountability to the community is enhanced. Citizens can more easily monitor the implementation of projects and hold local leaders accountable for resource utilization and outcomes, reducing corruption and ensuring that benefits reach the intended beneficiaries.
4. Empowerment of Marginalized Groups: Participation in local planning processes empowers marginalized groups by giving them a stake in governance and development. It builds their capacity to articulate demands, negotiate, and influence decisions that affect their lives, thereby challenging existing power structures and promoting social equity.

In conclusion, decentralized planning, by fostering local ownership, participation, and responsiveness, creates a virtuous cycle where economic development is not only more efficient and sustainable but also inherently more equitable and inclusive, leading to greater social justice. It moves away from a 'one-size-fits-all' approach to development, recognizing the diversity of needs and aspirations at the grassroots.