The statute was stretched
On this page14
The section was read as reaching key blanks generally
It describes a key suited to a lock adopted by the Postal Service and in use on the mails, or a key to an authorized mail receptacle.
Which is three qualifiers in the first limb
Suited to, adopted by, and in use on. All three, and a commercial padlock key fails the second.
A blank was assumed to be a key
The first limb turns on being suited to a lock, and an uncut blank is not suited to anything. That is what makes it a blank.
The intent element was dropped
The possession branch requires an intent unlawfully or improperly to use, sell or otherwise dispose of the thing. Possession alone is not the offence as described.
And unlawfully and improperly were treated as one word
They sit alongside each other in the clause and are not the same. Improperly is broader and softer.
A packaging requirement was looked for in it
There is none. No marking, no labeling and nothing about a container anywhere in the section.
Which is the finding rather than a gap
This is the group where the honest answer is that the federal provision naming a key is about a crime, and the container question stands alone.
Locksmith licensing was assumed to be federal
It is a state matter and varies, and it is what actually governs who may do this work.
And restricted keyways were assumed to be legal
They are a commercial arrangement, and nothing here describes how they operate or what force they have.
A mark was assumed to have effect
Whether anything such as do not duplicate has legal effect is not answered on these pages either way.
And this property was expected to help with a lock
It does not, and that is deliberate. Nothing here would assist anybody in defeating one.
Read the section for what it is
A theft and forgery provision with a ten year maximum, quoted because it is the federal law that names a key.
Then read the material
Which is the part this catalog can actually answer, and the answer is 56 of 251 containers.