The arrest and deportation to Mexico of an illegal immigrant who took sanctuary in a Chicago church to remain near her American-born son has become the latest flashpoint in the nation’s immigration debate, with proponents of more liberal immigration laws criticizing the action as heartless and unnecessary, and opponents praising it as long overdue.

Elvira Arellano, 32, was holed up with son Saul, 8, in Adalberto United Methodist Church in Chicago for a year before announcing at a news conference last week that she was leaving the church to lobby American lawmakers. She was arrested Sunday in downtown Los Angeles after speaking at a rally and attending a Mass.

Immigration advocates have cited the predicament of a mother and son being hunted by authorities as a symbol of the unfairness of the country’s tougher enforcement approach on illegal-immigrant working families and their American-born children. Their situation also inspired a revival of the religious sanctuary movement among congregations in 50 American cities.

Ms. Arellano’s arrest draws “renewed attention to the plight of hundreds of thousands of families who are in the same situation,” said the Reverend Alexia Salvatierra, national coordinator of the Los Angeles-based New Sanctuary Movement, which invited Ms. Arellano to speak to its members. She said Ms. Arellano represents “families with U.S.-citizen children, with a long work record in this country, no criminal history, and who are part of the fabric of our country, who face the prospect of having parents ripped away from their kids.”

Ms. Arellano was deported shortly after entering America illegally in 1997, then she re-entered. She worked in Washington state and gave birth to her son, separated from his father, and in 2000 went to Chicago, where she cleaned planes at O’Hare International Airport.

She was arrested in 2002 and convicted of working under a false Social Security number during a review of airport personnel after the September 11, 2001, attacks. That conviction prompted a deportation order; Ms. Arellano was to surrender to authorities last August but instead sought refuge at the church.

Opponents called her deportation a belated step by the Bush administration to uphold the rule of law.

“This woman knowingly violated the law and lived in the U.S. illegally,” said Steven Camarota, a spokesman for the Center for Immigration Studies, a Washington think tank that advocates less immigration. “She was deported, knowingly violated the law and came back.”