DALLAS (CBS11) – It’s the cities vs. the state at federal court in San Antonio.

Opponents, including the City of Dallas, want a federal judge to block the Texas law banning sanctuary cities, also known as Senate Bill 4, from going into effect September 1.

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Outside the courthouse, people fighting the law chanted, “We will not accept the racism imbedded in SB4 not today, not ever.”

They call the law discriminatory because they believe it unfairly targets Latinos.

Under SB4, police officers will be allowed to ask people they detain about their immigration status.

The law also makes it illegal for police departments to continue their policies banning officers from asking about a person’s immigration status when they are detained.

Jose Santoyo, a Dreamer whose parents brought him to the U.S. when he was five years old said, “If you’re driving while brown, you get pulled over, you get taken to jail, and then you get an immigration hold, that’s what racial profiling looks like. We don’t want that to happen in Texas.”

He and other opponents also argue victims and others won’t report crimes because they’ll be too scared to call police.

But supporters say the law only targets criminals who are in the U.S. illegally.

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Cathie Adams, a member of the conservative group Eagle Forum said, “We have too many times where those who are here illegally have been sent back to their home nations and then have returned again illegally and are being harbored in sanctuary cities and then there is a crime against an American citizen. This is a security issue.”

Santoyo said the Texas law is already having a negative impact on the Latino community.

He says a friend of his told him that he and his family are returning to Mexico because they are scared of what could happen to his family under the law.

“So he came to this country with the idea that he was somehow going to be able to adjust his status and work and make something out of himself and provide for his family, that didn’t happen over the years because immigration reform never panned out,” said Santoyo.

“We’ve always been a melting pot and I think this nation always will be, but come and follow the rule of law,” said Adams. “Otherwise, what you have fled because there was no rule of law, there was no ability and a free market to make a living and support your family, those things will go away here.”

The U.S. Justice Department is supporting the Texas law in federal court and believes it’s constitutional.

Some legal experts predict this issue will make it all the way to the U.S. Supreme Court.

Texas Attorney General Ken Paxton has requested a federal judge in Austin to declare the law constitutional.

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A hearing on that is set for Thursday.