Those advocates say a number of federal prisons are cutting library hours and library staff or closing the facilities entirely.
"Access to books is really important, and what we're seeing is an erosion in access to books," Correctional Investigator Howard Sapers told CBC News.
Prisons across Canada are cutting back access, in part a result of security concerns because of overcrowding. It's harder to move inmates safely from one part of the institution to another if there are too many inmates for the number of guards, Sapers said.
Budget cuts are also affecting access to library materials.
Last year, the Saskatchewan Penitentiary in Prince Albert, Sask., didn't extend a contract with the region's library service, shutting down access for inmates. The library was open five days per week in the afternoons and evenings and inmates would borrow, on average, about 50 items per day. The program cost about $70,000 a year.
Several other institutions in Ontario and Quebec have seen library access restricted or cut entirely.
Advocates say reading material is vital for people living behind prison walls. There's little to do to pass the time.
Plus, many inmates need to improve their literacy skills for when they're released. Libraries are one of the only ways to get books because inmates can't keep much in their cells, and there are security risks with accepting books donated by family members.
Already low literacy skills
Reading is "a huge part of our development as human beings," said Joan McEwen, a lawyer who has taught a creative writing class at the Matsqui Institution near Vancouver.
"It's a big part of how we become civilized and cultured, and what better thing to do in prison in your... downtime than read? It's stimulating and you can have conversations with people, you learn about the world, you become more pro-social."
Pro-social is a term used often by those working with inmates. It refers to positive behaviours, and it's something the Correctional Service of Canada aims to cultivate in inmates before they're released.
Sapers said reading helps prisoners in their rehabilitation.
"The average level of educational attainment is Grade 8 or lower, but you need Grade 8 or higher literacy skills to successfully participate in most correctional programs," he said.
Carol Finlay, a former English teacher and an Anglican minister, started her first book club in the Collins Bay Institution in 2009. By the end of this month, she'll have 17 book clubs operating at 14 prisons across Canada.
A spokeswoman for the Correctional Service of Canada said library services are still available in all federal institutions.
Asked specifically whether inmate trips are limited, hours and librarian staff jobs cut back or inmate library positions cut back, she responded that "the management and availability of library services are determined at an institutional level based on the security of the institution and operational requirements."
"The Correctional Service of Canada (CSC) recognizes the benefits of education and literacy which provides offenders with greater opportunities to participate in other programs offered by CSC and to become law-abiding citizens," CSC spokeswoman Sara Parkes wrote in an email.
"The mandate of CSC is to contribute to public safety by actively encouraging and assisting offenders to become law-abiding citizens, while exercising reasonable, safe, secure and humane control. CSC assists offenders in managing all aspects of daily life including activities that promote pro-social values and behaviour as part of the rehabilitation process."
While inmates are provided an hour of exercise every day, Parkes said there is no stated minimum for hours of access to libraries.
'My roommate is going to read to me'
But the need is there, according to a woman who has volunteered in federal and provincial institutions.
Kirsten Wurmann has been making sure people behind bars get books since 2007, first at a federal institution in Edmonton and then in Winnipeg at its provincial remand centre.
Wurmann said the inmates appreciate having access to books and recalled one man who took his time carefully examining every book she'd brought in.
"I was asking, 'Do you need some help finding something? Is there a particular author you might be interested in?' and he said, 'Oh, I don't read, but my roommate is going to read to me,' " Wurmann said.