Here are the purposes of pre-emption rights as per law:

Protective Purposes
1. Maintain Control: Prevent dilution of ownership and control.
2. Protect Shareholder Value: Ensure existing shareholders maintain their investment value.
3. Prevent Market Volatility: Limit sudden changes in share price.
4. Safeguard Minority Shareholders: Protect minority shareholders from oppression.

Regulatory Purposes
1. Compliance with Securities Laws: Fulfill securities laws and exchange requirements.
2. Transparency and Disclosure: Ensure transparent disclosure of pre-emption rights.
3. Protection of Investors: Safeguard investors from unfair practices.

Economic Purposes
1. Preserve Liquidity: Maintain liquidity for existing shareholders.
2. Encourage Long-term Investment: Incentivize long-term investment.
3. Reduce Risk: Minimize risk of losses due to dilution.

Other Purposes
1. Prevent Insider Trading: Prevent insider trading and market manipulation.
2. Promote Fair Treatment: Ensure fair treatment of all shareholders.
3. Support Corporate Governance: Enhance corporate governance standards.

Specific Laws and Regulations
1. Securities Act 1933 (US): Requires pre-emption rights for existing shareholders.
2. Securities Exchange Act 1934 (US): Regulates pre-emption rights for publicly traded companies.
3. European Union’s Prospectus Directive: Requires pre-emption rights for existing shareholders.
4. Canada’s Securities Act: Regulates pre-emption rights for publicly traded companies.

Key Considerations
1. Regulatory compliance
2. Tax implications
3. Shareholder agreement
4. Board approval
5. Transparency
6. Disclosure requirements
7. Shareholder approval
Consult with legal, financial, and regulatory experts to ensure compliance and optimal design of pre-emption rights in your jurisdiction.