Travellers under Canada's Nexus program who are considered low-risk have been caught trying to illegally smuggle goods into the country, newly released documents show.

The Nexus program allows Canadian residents to pass through special lines when travelling to the United States.

It's designed to make border patrol more efficient by allowing guards to move those who aren't considered to be a danger to border security through customs more quickly and focus on travellers who have the potential to be high-risk.

But the documents show more than a hundred Nexus travellers crossing the border in the second half of 2010 said they had no goods to declare or undervalued the goods they were declaring, only to later be found to be smuggling the items.

A border officer fills out what's called an alternative program inspection violation card every time a Nexus traveller is found to be breaking the law. The document details the violation a cardholder has committed.

The Canadian Press obtained copies of the cards filled out in 2010 for smuggling under the Access to Information Act from the Canada Border Services Agency, the area of the federal government responsible for border patrol.

The smuggled goods detailed in the cards range anywhere from a couple of undeclared bottles of beer to a $16,000 engagement ring.

Other examples include an Ontario resident who attempted to declare a boat as Canadian goods when a customs officer found out it was actually being imported and a Quebec traveller who bought tires online from a business in the United States and had them installed on his car but never declared them.

The travellers occasionally gave excuses for their attempts to break the law.

One Nexus member "didn't declare two cartons of cigarettes and food" and "stated she was tired and not aware of the exemptions," the comments section of one of the forms reads.

Another "driver admitted to willingly not declaring goods because customs 'is a hassle,"' reads another.

The travellers had their Nexus passes revoked in most cases.

The CBSA conducts yearly "risk assessments" of members to ensure they continue to be unlikely to smuggle after they are initially approved for the five-year program, said a CBSA spokesperson.

Esme Bailey added 410 Nexus travellers had their memberships revoked in 2010. Nexus members crossed the border 3,819,757 times during that time.

The CBSA does not keep track of how many Nexus travellers are caught smuggling each year.

Some say the smuggling cases are evidence the federal government needs to review its process for inspecting members of the program at the border.

"If you wanted to be a smuggler, probably the first thing you'd want to do is enrol in the Nexus program because a lot of the time you're going to have a lot freer movement," said Benjamin Muller, an expert on border security and a professor at King's University College in London, Ont.

Muller said he registered for the Nexus program when he was doing research on border security. He crossed the border between British Columbia and the United States every day for five months and was never searched, he said.

The CBSA needs to employ enough border guards to ensure travellers who use Nexus are following the rules, said Ron Moran, President of the Customs and Immigration Union, the country's union of border security guards.

"If you're running a program like Nexus and you don't have enough resources to undertake an acceptable level of compliance verification then it becomes a very precarious, a very dangerously precarious, situation," he said.

The CBSA's main tool for ensuring compliance is to set up at a given border crossing and search a certain number of travellers crossing the border that day, said Moran. Unless border guards have a specific piece of intelligence that flags you as a security threat, he said, Nexus travellers are otherwise rarely searched at the border.

In spite of that, Muller said you are more likely to be stopped if you are a member of the Nexus program because there are far more people who are not members.

The concerns come just a few years after a May 2008 internal evaluation conducted by the CBSA showed border guards feared the Nexus program had become a "licence to smuggle."

The federal government is planning to hire about 327 new employees for the CBSA by 2014, according to figures released by the Parliamentary Budget Office.

Of those, 53 will be used to increase the number of people they catch smuggling "inadmissible" goods into the country, a report published by the Treasury Board showed.

In order to qualify for the Nexus program, applicants cannot have a criminal record or have violated customs or immigration laws.

Canadian applicants are then required to submit to an interview with a United States Customs and Border Protection officer and have the irises in their eyes scanned. A $50 fee is also required.

The Nexus program began as a joint venture of the Canada and U.S. governments in 2000. It has over 500,000 members, according to testimony at a House of Commons committee by CBSA director general Maureen Tracy, a number the agency hopes will reach 830,000 by 2015.