But the premier says there's no contradiction between what she says now and what she said then.
Opposition Liberals raised a 1998 policy on school integration that was signed by Marois when she was the provincial education minister.
In it, she encourages the "visibility" of religious diversity "by school personnel."
She goes on to note in the 40-page document, which was co-signed by then-immigration minister Andre Boisclair, that the province's "common values" include "openness to diversity in ethnocultural, linguistic and religious matters."
"The credibility of the discussion over the openness of ethnocultural and religious diversity is supported in good part by the visibility of this diversity among school staff," the document says.
The document also states that "the mere wearing of the hijab cannot be prohibited in Quebec schools" because it does not break any laws or the Canadian or Quebec charters of rights.
Under the values charter proposed by Marois' government, religious headwear such as hijabs would be banned in schools.
The charter, which still has to be passed by the provincial legislature, would ban public sector employees from wearing any obvious religious objects or clothing.
The Liberals contend that the stand by the current Parti Quebecois government is in complete contradiction to Marois' position in 1998.
Marois told the legislature on Thursday there's no contradiction in her remarks, pointing out the 1998 policy has no references to overt religious symbols such as those that would be banned in the values charter.
"Never, never in this document do we speak of religious symbols," she said. "Ever. In fact, I am very consistent because it is not in this document but in the charter that we limit the wearing of obvious religious symbols and we do so out of respect for everyone."
She said the government has always promoted a policy of a Quebec that includes everyone.
Liberal House Leader Jean-Marc Fournier says the PQ's proposed charter of values only serves to rupture the overtures made during the last 15 years.
He said that inclusion has been a cornerstone of Quebec's dealings with its citizens, whether it be in the views of the premier when Marois was education minister, the recommendations of the Bouchard-Taylor commission on reasonable accommodation or recent statements by the Quebec human rights commission.
"Now you want to impose a dress code that goes against the historical approach without study, without science," Fournier said. "Why?"
In the 1990s, the PQ was in damage-control mode after remarks by then-premier Jacques Parizeau on the night of the sovereigntist loss in the 1995 referendum. Parizeau blamed the defeat on "money and the ethnic vote."
After that, the PQ pushed what it described as "civic nationalism."
The minister charged with defending the proposed charter sprung to Marois' defence on Thursday.
Bernard Drainville says there's no contradiction in opinion.
"If we have a charter of Quebec's values on secularism, it is because Pauline Marois is premier of Quebec," said Drainville. "It is because she made it a priority for her government. It is thanks to her courage, we have a charter in Quebec and this is what we should focus on, we should focus on the present."