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Two reasons

Two reasons

By Dwight Davis, Founder

On this page12
Protection, and the machines. That is the whole statutory list.

The requirement

Regulations effective to prevent the nonfunctional-slack-fill of packages containing consumer commodities.

And the statutory definition

A package shall be deemed to be nonfunctionally slack-filled if it is filled to substantially less than its capacity for reasons other than (A) protection of the contents of such package or (B) the requirements of the machines used for enclosing the contents in such package.

Two reasons

Protection, and the machines. Nothing else appears in the statute.

The FDA regulation gives six

21 CFR 100.100(a), which the pet food and treats property quotes in full, adds unavoidable settling, a specific package function, a reusable container of independent value, and inability to reduce the package further.

So the statutory list is the narrow one

Which is the opposite of the usual relationship, where a regulation tightens a statute rather than loosening it.

And settling is the reason that is missing

Which for a dry powder is the reason that matters most. A product that packs down in transit is relying on something the statute does not name.

Substantially less than its capacity

Is the statutory threshold, and substantially is doing work that no number does. The regulation uses the same framing and supplies more exceptions rather than a figure.

Which means neither definition gives you a percentage

There is no permitted fraction of empty space anywhere in either. The test is the reason, not the amount.

Our capacity figure is the reference point for both

Filled to substantially less than its capacity. Capacity is the field we publish, on 169 of 171 containers here.

Substantially is the word doing the work

Which is a judgment rather than a fraction, and it is the same framing in both texts. Neither one tells you how much empty space is too much.

And the fill is the number you measure

After settling, in the container you will ship. The pet food property sets out the six-reason version of this analysis in detail.

References

15 U.S.C. 1454(c)(4), requiring regulations effective to "prevent the nonfunctional-slack-fill of packages containing consumer commodities", with the statutory definition: "a package shall be deemed to be nonfunctionally slack-filled if it is filled to substantially less than its capacity for reasons other than (A) protection of the contents of such package or (B) the requirements of machines used for enclosing the contents in such package." The FDA regulation at 21 CFR 100.100(a) gives six functional reasons rather than two; the pet food and treats property quotes all six. law.cornell.edu
The Davis Pack Supply catalog, measured 19 October 2026. Our capacity field is a volume in millilitres, published on 169 of the 171 containers in this group and running 100 to 3,000 mL with a median of 355. A powder supplement is declared by weight. We publish no bulk density and no fill weight, so a volume cannot be converted to a mass from our data. Bulk density is a property of the powder, and the five leaves in this group differ widely in it.
Written from 15 U.S.C. 1454(c) and from the catalog as it stood on 19 October 2026. That subsection authorizes regulations and is not itself a packaging requirement; nothing here describes the content of any regulation promulgated under it. Our capacity field is a volume and a powder is declared by weight, and we publish no bulk density, so the two cannot be reconciled from our data. Whether any ingredient in this group may be used is the new dietary ingredient question covered in the adjacent botanicals property and is not addressed here.