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Privacy Compliance

Disclaimer: This skill provides engineering and product implementation guidance only. It is not legal advice. Consult qualified legal counsel for compliance decisions specific to your organization, jurisdiction, and use case.

A practical framework for engineers and product teams building privacy-compliant systems. Covers GDPR, CCPA, consent management, data subject rights, DPIAs, and cross-border transfer mechanisms - with emphasis on what to build and how to structure it, not just regulatory theory.

When to use this skill

Trigger this skill when the user:

1. Asks how to implement GDPR or CCPA compliance for a product
2. Needs to design a cookie banner, consent manager, or preference center
3. Wants to conduct or template a Data Protection Impact Assessment (DPIA)
4. Needs to handle a Subject Access Request (SAR), deletion, or portability request
5. Is writing or reviewing a privacy policy
6. Needs to implement data retention or deletion schedules
7. Is configuring cross-border data transfers (SCCs, adequacy decisions)

Do NOT trigger this skill for:

• General security hardening unrelated to personal data (use the backend-engineering skill)
• IP law, contracts, or employment law - these require specialized legal counsel

Key principles

1. Privacy by design - Build privacy controls into the architecture from day one. Data minimization, access controls, and audit logs are structural decisions, not features added after launch. Retrofitting is expensive and incomplete.

2. Data minimization - Collect only what you need, retain it only as long as necessary, and delete it on schedule. Every field in your database is a liability if you cannot justify its purpose and retention period.

3. Lawful basis for processing - Every processing activity must have a documented lawful basis (GDPR) or a disclosure obligation (CCPA). "We might need it someday" is not a lawful basis. Document the basis before you collect the data.

4. Transparency - Users must understand what data you collect, why, how long you keep it, and who you share it with. Privacy policies must be readable, not a legal wall. Consent must be informed to be valid.

5. Accountability - Maintain records of processing activities (RoPA), run DPIAs for high-risk processing, appoint a DPO when required, and respond to data subject requests within statutory deadlines. Compliance is a continuous process, not a one-time audit.

Core concepts

GDPR vs CCPA at a glance

Lawful bases for processing (GDPR Art. 6)

Data subject rights

Cross-border transfer mechanisms

Common tasks

1. Implement a GDPR compliance checklist

Use this as a product/engineering launch gate:

Data inventory

• Record of Processing Activities (RoPA) created and up to date
• Lawful basis documented for each processing activity
• Retention periods defined for each data category
• Third-party processors identified; DPAs signed with each

Technical controls

• Personal data encrypted at rest and in transit
• Access to personal data is role-based and audited
• Pseudonymization applied where full identification is not needed
• Automated deletion jobs scheduled per retention policy

User-facing obligations

• Privacy policy published, accessible, and up to date
• Cookie consent mechanism in place (see task 2)
• Data subject request workflow implemented (see task 4)
• Age verification where required (special categories, children's data)

Organizational

• DPO appointed (if required) and contact details published
• Data breach response procedure documented and tested
• DPIA completed for high-risk processing activities (see task 3)
• Staff privacy training completed

2. Design consent management (cookie banners and preference center)

The consent bar is higher than most implementations meet. For GDPR, pre-ticked boxes, bundled consent, and making "reject" harder than "accept" are all invalid.

Cookie categories to surface to users:

Implementation requirements:

Banner must:
- Appear before any non-essential cookies are set
- Present accept and reject options with equal prominence
- Link to full privacy policy and cookie policy
- Allow granular category-level choice (not just accept all / reject all)
- Record consent with timestamp, version, and signal (for audit)

Preference center must:
- Be accessible from footer at any time
- Allow withdrawing consent as easily as giving it
- Persist preferences across sessions (store in first-party cookie or server-side)
- Respect GPC (Global Privacy Control) signal for CCPA opt-out

Consent record schema (minimum):

{
  "user_id": "...",
  "session_id": "...",
  "timestamp": "2024-01-15T10:23:00Z",
  "policy_version": "2.3",
  "signal": "explicit_accept",
  "categories": {
    "strictly_necessary": true,
    "functional": true,
    "analytics": false,
    "marketing": false
  },
  "geo": "DE",
  "ip_hash": "sha256(...)"
}

3. Conduct a DPIA (Data Protection Impact Assessment)

A DPIA is mandatory under GDPR Art. 35 when processing is likely to result in a high risk to individuals. Always required for: systematic profiling, large-scale sensitive data processing, systematic monitoring of public areas.

DPIA template:

1. DESCRIPTION OF PROCESSING
   - Purpose(s) of the processing
   - Nature of the processing (collection, storage, sharing, deletion)
   - Scope: data categories, volume, frequency, retention
   - Context: who are the data subjects? Are they vulnerable?
   - Recipients: internal teams, third-party processors, public

2. NECESSITY AND PROPORTIONALITY
   - Is each data element strictly necessary for the stated purpose?
   - Could a less privacy-invasive approach achieve the same outcome?
   - What is the legal basis? Is it proportionate to the risk?
   - What retention period is justified?

3. RISK IDENTIFICATION
   For each risk, assess: likelihood (Low/Medium/High) x severity (Low/Medium/High)
   - Unauthorized access or data breach
   - Inadvertent disclosure to wrong recipients
   - Excessive collection beyond stated purpose
   - Inability to fulfill data subject rights
   - Re-identification of pseudonymized data
   - Discrimination or unfair automated decisions

4. RISK MITIGATION MEASURES
   - Technical: encryption, access controls, pseudonymization, audit logs
   - Organizational: training, DPAs with processors, incident response plan
   - Process: retention schedules, DSR workflow, breach notification procedure

5. RESIDUAL RISK AND SIGN-OFF
   - Residual risk level after mitigations: Low / Medium / High
   - If residual risk remains High: consult supervisory authority before proceeding
   - Sign-off: DPO (if applicable), Legal, Engineering, Product owner
   - Review date: (recommend annually or on significant change)

4. Handle data subject requests (SAR, deletion, portability)

Response deadlines: 30 days (GDPR), 45 days (CCPA), both extendable once by an additional 30-45 days with notice to the requestor.

Identity verification: Verify identity before fulfilling any request. For authenticated users, session confirmation is sufficient. For unauthenticated requests, ask for information already held (e.g., email + last 4 of payment card). Do not ask for more data than needed to verify.

Request types and implementation:

Subject Access Request (SAR / Right to Know):
- Export all personal data held across: primary DB, data warehouse,
  analytics tools, marketing platforms, support tickets, backups*
- Include: categories of data, purposes, retention periods,
  recipients/third parties, source of data if not collected directly
- Format: machine-readable (JSON/CSV) + human-readable summary
- *Note: you must describe backup data; you are not required to restore
  a backup solely to fulfill a SAR

Erasure / Right to Deletion:
- Delete from primary store, read replicas, analytics, marketing platforms
- Notify all processors and sub-processors
- Exceptions: data held for legal obligation (tax, fraud) may be retained
  with processing restricted; document the exception
- Backups: document policy (e.g., "purged within 90 days as backups rotate")
- Send confirmation to requestor with scope of deletion

Portability (GDPR Art. 20 / CCPA):
- Applies to data the user provided (not inferred data under GDPR)
- Format: structured, commonly used, machine-readable (JSON preferred)
- Must include all user-provided + observed behavioral data

Request tracking minimum fields:
- Request ID, type, date received, requestor identity verified (boolean)
- Date fulfilled / extended / denied, reason if denied, response sent (boolean)

5. Write a privacy policy

A compliant privacy policy must be concise, transparent, and written in plain language. Structure it as follows:

6. Implement data retention policies

Every data category needs a documented retention schedule enforced by code, not just policy documents.

Retention decision framework:

For each table / data category:
1. What is the purpose of this data?
2. Is there a legal minimum retention? (e.g., financial records: 7 years)
3. Is there a legal maximum? (e.g., GDPR's storage limitation principle)
4. When does the retention clock start?
   - Date of collection, last interaction, end of contract, or legal obligation end
5. What deletion action is taken?
   - Hard delete: remove the row entirely
   - Anonymization: replace PII fields with null/hash - retain for analytics
   - Archival: move to cold storage, restricted access, then delete at archive TTL

Enforcement pattern:

// Scheduled job (daily or weekly)
function runRetentionPolicy():
    for each retention_rule in retention_schedule:
        records = db.query(
            "SELECT id FROM " + rule.table +
            " WHERE " + rule.clock_column + " < NOW() - INTERVAL '" + rule.period + "'" +
            " AND NOT has_legal_hold"
        )
        for each record in records:
            if rule.action == "delete":
                db.hardDelete(rule.table, record.id)
                auditLog("retention_delete", rule.table, record.id)
            else if rule.action == "anonymize":
                db.anonymize(rule.table, record.id, rule.pii_columns)
                auditLog("retention_anonymize", rule.table, record.id)

7. Manage cross-border data transfers

Decision tree:

Is the destination country on the EU adequacy list?
  YES -> Transfer permitted. No additional mechanism required.
        (Maintain documentation confirming adequacy status.)
  NO  -> Is it an intra-group transfer?
    YES -> Consider Binding Corporate Rules (BCRs)
           - Long approval process; only viable for large multinationals
    NO  -> Use Standard Contractual Clauses (2021 SCCs)
           - Use Module 1 (controller to controller)
           - Use Module 2 (controller to processor) - most common
           - Conduct Transfer Impact Assessment (TIA) for high-risk destinations
           - Implement supplementary measures if TIA shows elevated risk
             (e.g., encryption where processor cannot access keys)

Transfer Impact Assessment (TIA) - key questions:

• Does the destination country have laws enabling government access to data?
• What is the legal remedy available to EU individuals?
• What supplementary technical measures would reduce the risk (e.g., end-to-end encryption, pseudonymization, data minimization before transfer)?

Anti-patterns

References

For detailed side-by-side regulatory comparison, load the relevant reference file:

• references/gdpr-ccpa-comparison.md - Full GDPR vs CCPA requirements table with article citations, thresholds, and implementation notes

Only load the reference file if the current task requires deep regulatory detail - it is long and will consume context.

Related skills

When this skill is activated, check if the following companion skills are installed. For any that are missing, mention them to the user and offer to install before proceeding with the task. Example: "I notice you don't have [skill] installed yet - it pairs well with this skill. Want me to install it?"

• regulatory-compliance - Preparing for SOC 2, HIPAA, or PCI-DSS compliance, conducting audits, or implementing security controls.
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