Silencers are illegal, but licence-able weapons have them.
And I thought the invisible underwear was also legal? Can't recall, away from books. Same deal as the Sleeping Tiger, Ruthenium simply comes with the Legal Armor.
*shrug*
The legal codes all change based on where the campaign is set anyway. And most Shadowrunner PCs are committing a felony just sitting around in their apartment in their PJs watching Trid.
Silencers are not a good example. As their status depends on state/county/country. In Texas for example, a silencer is a legit safety device BECAUSE it reduces the decibel level of a gun shot by up to 70%.
(Contrary to popular opinion, a Silencer does NOT make a firearm silent -except for 6 specific cases- they just reduce the noise by 40 to 70%.)
In Canada, you require an unrestricted licence to own a silencer... but then again, you need an unrestricted license to own most firearms that you would want a silencer on anyways..
I am trying to think of something that by itself is illegal, but not when in an other similar form...and I can't. Probably because it makes no sense.
If wool was made illegal because its inhumane to shear sheep, why would Walmart be allowed to sell wool socks???
They even FLAT OUT TELL YOU that ruthenium is FORBIDDEN in its availability.... then commercially sell it as clothing.... Why the fuck did they make it illegal if they are going to sell you underwear made from it?

No.
More then likely its a case of left hand, right hand... neither knows what the other has done, and the community is left scratching their head.
EDIT:
originally on phone, and got locked into caps lock and didn't realize until an entire sentence was written.. fixed now that i am on desktop. Also fixed spelling.