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ALVARADO (CBSDFW.COM) – Dozens of Texas cities are seeing their sex offender residency restrictions challenged. The advocacy group Texas Voices for Reason and Justice said that it sent letters to 46 cities. At least a quarter of them are in North Texas.

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The letters threaten litigation if residency restrictions are not repealed by December 19.

The group points to a 2007 opinion by then Attorney General Greg Abbott that “a general-law municipality may not adopt an ordinance restricting where a registered sex offender may live.”

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The term “general-law municipality” refers to cities with a population of fewer than 5,000 people and no charter. According to the Texas Municipal League, about 75 percent of all Texas cities fall into this category.

Alvarado’s city council reviewed its ordinance during a meeting on Monday night, but chose not to take action. They currently ban sex offenders from living within 2,000 feet of a school, playground or park. The city already backed down earlier this year on enforcing a requirement that sex offenders post signs on Halloween.

A registered sex offender — who spoke on the condition of anonymity — attended the meeting. An avid reader, he said that he would like to be able to visit the public library. He told CBS 11 News that he became a registered sex offender after touching a girl when he was 12 years old.

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While he thinks that certain restrictions should be relaxed, he said that he feels others are needed. “I’ve known real hardcore sex offenders while I was incarcerated. They need to have a sign up,” he said.