New York Department store Century 21 is accused of mislabeling fur garments. (Slaven Vlasic/Getty Images)

Retailer Century 21 said it's not responsible for mislabeled fur products sold in its department stores.

"Century 21 does not create garment labels, the manufacturers do. It is the manufacturer's responsibility to provide an accurate account of materials used in the garment and to be transparent with the consumer before his or her purchase," Century 21 said in a statement to ABCNews.com.

But a New York state legislator and the U.S. Humane Society see it differently.

"It's the ultimate responsibility of the retailer," New York assemblywoman Linda B. Rosenthal told ABCNews.com. "They know what they're purchasing. They have to make sure that it's properly labeled."

Rosenthal wrote the law that was passed in 2007 that made it illegal in New York to sell or manufacture garments with any quantity of fur that was not properly labeled as faux fur or real fur.

"I wanted to make it crystal clear for consumers who often choose to buy something based on whether it's real or faux fur," Rosenthal said. "It can be hard to tell."

To take the guesswork out of it, the New York law required that both manufacturers and retailers become responsible for labeling fur-bearing garments, whether that meant doing so on a label, hangtag or sticker.

Century 21 first came under Rosenthal's radar when it opened stores in New York and did not respond to Rosenthal's welcome letter reminding the retailer of New York's fur-labeling law. Consumers later came forward, Rosenthal said, informing her that Century 21 was not labeling its garments correctly.

In January, Rosenthal and Pierre Grzybowski, research and enforcement manager of the fur-free campaign for the U.S. Humane Society, conducted a joint undercover investigation of Century 21 department stores in New York City.

Grzybowski has led several investigations of retailers throughout the nation, including Bloomingdale's, Saks Fifth Avenue and Bergdorf Goodman.

"One of my main job responsibilities is to protect consumers and animals by uncovering misrepresented animal fur," Grzybowski told ABCNews.com. With every investigation, Grzybowski said he found animal fur either falsely advertised, falsely labeled, unlabeled or misrepresented by sales staff.

"Real fur is the animal skin with the fur still attached," Grzybowski said. "Fake fur is a mesh or fabric backing with the fibers woven into it."

In September, Grzybowski ordered three Marc by Marc Jacobs jackets, advertised on the Century 21 website as having "faux fur trim." When they arrived, the jackets' labels read "100% REAL RACCOON FUR COUNTRY OF ORIGIN CHINA." A lab test of one of the Marc by Marc Jacobs jackets showed the presence of raccoon dog, Grzybowski said.

Upon this discovery, the Humane Society and Rosenthal took their investigation to two brick-and-mortar stores in New York City later in January. Grzybowski said he could spot real fur in several garments that were labeled by Century 21 as "faux fur" or not labeled by the retailer or the manufacturer at all.

Later tests by the Humane Society's lab indicated the garments contained real fur.

"The reason this is so important is because animals are horribly mistreated for fur production. So a consumer who wants to avoid supporting live skinning of raccoon dogs shouldn't have to worry about getting duped by ads or labels," Grzybowski said.

Both Grzybowski and Rosenthal believe that retailers are just as responsible as manufacturers for making sure that everything they sell is correctly advertised and labeled in accordance with New York state law.

"This is a cautionary tale for other retailers. Consumers deserve to know what they buy," Rosenthal said.

The investigation into Century 21's fur-labeling practices is only the most recent, Grzybowski said. "Unfortunately," he said, "we don't think it's going to be the last."