Privacy Commissioner of Canada's guidelines for fingerprint use

Covert collection: People should be informed if their personal information is being collected.
Cross-matching: Personal information should only be used for the purpose for which it was collected.
Secondary Information: Personal information should only be collected for a clearly identified purpose.

smell test:
Necessity: Is the measure demonstrably necessary to meet a specific need?
Effectiveness: Is it likely to be effective in meeting that need?
Proportionality: Would the loss of privacy be proportionate to the benefit gained?
Alternatives: Is there a less privacy-invasive way of achieving the same end?

guidelines for implementation:
record only summary information
use only for verification, not identification
store locally, rather than in central databases