The things Americans can’t sell

In an effort to curb a boom in wildlife trafficking, the Obama administration has announced plans to tighten up a ban on the sale of ivory.

The measure would prohibit the import, export or resale of elephant ivory, with few exceptions.

Ivory is just one example of a product that is not allowed in the marketplace due to laws protecting wildlife, historic or cultural properties. There are other bans on sales that are motivated by safety concerns, including a prohibition on the sale of recalled items of all sorts.

It's clear that the free market is not absolutely free for all.

The sale of drugs and firearms is typically regulated—and at times illegal. But there are other surprising items that may seem innocuous, yet are prohibited.

Before you look to sell items either for some extra cash or as a small business, it helps to know what the limitations are for an average citizen.

Click ahead to have a look at some objects that may once have been fine to sell, but are now forbidden.

—By Colleen Kane, Special to CNBC
Posted 21 Feb. 2014

(CLARIFICATION: The first slide of this slideshow has been modified to reflect that while some drugs and guns are illegal to sell, there certain types of guns and drugs that can be sold with restrictions.)

Chris Rousseau, of Highland Park, N.J. recently listed a Transformer robot toy from his childhood on eBay. To his surprise, he was soon notified that his auction of the Megatron generation 1 figure from 1984 had been taken down.

A message from eBay informed him of the reason. "The Megatron figure you listed transforms into a realistic-looking firearm and needs to have orange markings permanently attached by the manufacturer to the barrel in order to be sold on our site," it read.

Since 1988, U.S. law has required that toy and replica firearms have an orange plug inserted in the barrel, in hopes of preventing potentially deadly confusion with real firearms.

Dreamcatcher enthusiasts, don't be alarmed—they aren't all prohibited. However, sales of feathered items are restricted in the U.S., so if that dreamcatcher has dangling feathers of migratory birds such as a hawk or owl, it's not allowed. Feathers of captive-bred game birds like turkey are permitted.

Due to U.S. and international laws and regulations covering endangered and protected species, many other animal products are forbidden or restricted, such as polar bear skin rugs and many ivory products.

While they may still be turning up at yard sales around the country and appearing outwardly to be safe and sound, cribs made before June 28, 2011, do not meet regulations and are illegal to sell.

The Consumer Product Safety Commission proposed a ban on drop-side cribs in 2010, citing more than 30 deaths over a 10-year period, and more than 10 million drop-side-crib recalls since 2007. Some 14 crib companies had racked up more than 900 incident reports of drop-side cribs falling apart, injuring and killing infants. When the ban went into effect in 2011, CPSC Chairman Inez Tenenbaum told USA Today the rules are "a better approach than announcing recall after recall."

In the old days, no one wore helmets and toys were made of metal with sharp edges. One of the more egregious examples of casually dangerous games kids used to play was a set of airborne missiles intended to be tossed about at outdoor family events, often by drunken uncles, called lawn darts or Jarts. Over an eight-year period they were responsible for 6,100 trips to the emergency room.

Lawn darts were banned for a long time but got a reprieve to be marketed as an adults-only activity in the 1970s, lasting until a 7-year-old girl died from a lawn dart injury in 1987. Her father, David Snow, began campaigning against them, and they were banned again by the CPSC in 1988.

Oscar winners may be quick to thank the Academy when they win their prize, but down-on-their-luck recipients may have a different opinion later when they learn they can't sell their Oscar statuette for some needed cash.

Under a policy that has been in effect since 1950, winners must offer to sell it back to the Academy for $1 first. The same rule applies to the winner's heirs.

The official rules state: "Award winners shall not sell or otherwise dispose of the Oscar statuette, nor permit it to be sold or disposed of by operation of law, without first offering to sell it to the Academy for the sum of $1.00. This provision shall apply also to the heirs and assigns of Academy Award winners who may acquire a statuette by gift or bequest."

It won't pay to try to make a little cash on the side importing the Italian treat Kinder Surprise from visits to Europe or Canada.

The chocolate eggs, made by Ferrero, contain a small plastic toy hidden inside. They toy is considered a choking hazard, so they are prohibited by the U.S. under a ban on candies with embedded toys that's been in place since 1938.

In 2012, Chris Sweeney and Brandon Loo of Seattle were detained trying to cross the border from Canada back into the U.S. with six of the illegal goodies in the trunk of their car. The pair said they intended them as gifts for friends and family, but were told they could be fined up to $2,500.

If the law affecting Kinder Surprise ever changes, a market is apparently there, since according to an article on Yahoo, the U.S. Customs and Border Patrol confiscated 60,000 of the offending chocolate eggs from travelers in 2011.

The Native American Graves Protection and Repatriation Act attempts to return cultural artifacts and human remains found or unearthed on federal land after 1990. Because of that and a series of other federal laws, it's illegal to buy or sell anything that came out of a Native American grave on federal lands, and similar laws have passed on the state level.

Pieces excavated illegally from graves are considered more prized and enticing than everyday Native American artifacts. They are often betrayed by a "kill hole" made in the bottom at the time of burial.

"When in doubt, throw it out," is the credo the CPSC has for children's jewelry made out of metal.

A number of recalls of cheap children's jewelry found the pieces to have dangerous levels of lead, cadmium, and other harmful elements. Lead is an issue because lead poisoning in children can lead to irreversible brain damage, delay mental and physical growth and cause behavior, attention and learning problems.

Jewelry for children has a legal lead limit of 300 parts per million, but since there often is no way for consumers and many sellers to know how much lead or other dangerous elements may be present in such trinkets, it may be best to avoid it.

The CPSC says in its guide for resellers: "While you are not required to test your products for safety, resale stores, resellers (including those who sell on auction websites), and persons who give away used products for free cannot knowingly sell products that do not meet the requirements of the law."

The same issue can arise in painted items such as older toys and furniture. The legal limit for these items is 90 ppm.