In the BSA, Scouts learn how to use wood's tools (knife, saw and axe) and the privilege to carry and use them at Scouting activities, by earning a Totin' Chip card. (BSA Supply No. 34397)
From the reverse of the card -
This certification grants a Scout the right to carry and use woods tools. The Scout must show his Scout leader, or someone designated by his leader, that he understands his responsibility to do the following:
1. Read and understand woods tools use and safety rules from the Boy Scout Handbook.
2. Demonstrate proper handling, care, and use of the pocket knife, ax, and saw.
3. Use the knife, ax, and saw as tools, not playthings.
4. Respect all safety rules to protect others.
5. Respect property. Cut living and dead trees only with permission and with good reason.
6. Subscribe to the Outdoor Code.
The Scout's "Totin' Rights" can be taken from him if he fails in his responsibility.
The BSA does not have an "official policy" on sheath knives, though many Council camps do not allow them. Here is the BSA's "guidelines" on knives. This is taken from The Guide to Safe Scouting available online at the BSA's official website.
A sharp pocketknife with a can opener on it is an invaluable backcountry tool. Keep it clean, sharp, and handy. Avoid large sheath knives. They are heavy and awkward to carry, and unnecessary for most camp chores except for cleaning fish. Since its inception, Boy Scouting has relied heavily on an outdoor program to achieve its objectives. This program meets more of the purposes of Scouting than any other single feature. We believe we have a duty to instill in our members, youth and adult, the knowledge of how to use, handle, and store legally owned knives with the highest concern for safety and responsibility.
Remember—knives are not allowed on school premises, nor can they be taken aboard commercial aircraft.
YIS,
Gordy