Hazleton, PA measure on "illegal immigrants" has been blocked by a federal judge:

A federal judge on Thursday struck down the city of Hazleton's tough anti-immigration law, which has been emulated by cities around the country.

The Illegal Immigration Relief Act sought to impose fines on landlords who rent to illegal immigrants and deny business permits to companies that give them jobs. Another measure would have required tenants to register with City Hall and pay for a rental permit.

U.S. District Judge James Munley declared it unconstitutional Thursday and voided it based on evidence and testimony from a nine-day trial held in March.

According to his biography, Judge Munley seems to be a Clinton appointee. The text of the decision is here. Some key parts of the judge's decision (IIRA is Hazleton's "Illegal Immigration Relief Act" and the "RO" is the “Tenant Registration Ordinance”; the "Plaintiffs" are opponents of the measure):

Count I, the Supremacy Clause, we find FOR PLAINTIFFS. Federal
law pre-empts IIRA and RO.
Count II, Due Process, we find FOR PLAINTIFFS. IIRA and RO
violate the procedural due process protections of the Fourteenth
Amendment to the United States Constitution.
Counts III and IV, Equal Protection and the Fair Housing Act, 42
U.S.C. § § 3601, et seq., respectively, are DISMISSED. Neither IIRA nor
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RO facially discriminate on the basis of race, ethnicity or national origin.
Count V, 42 U.S.C. § 1981, we find FOR PLAINTIFFS. Illegal aliens
are “persons” under 42 U.S.C. § 1981. IIRA and RO impermissibly burden
their right to contract.
Count VI, Home Rule Charter Law, we find partially FOR
PLAINTIFFS, and we DISMISS partially. We find FOR PLAINTIFFS with
regard to the portion of IIRA which creates a private cause of action for a
dismissed employee. With regard to the other portions of IIRA and RO,
defendant did not act beyond its municipal powers, and we DISMISS that
portion of the count.
Count VII, Pennsylvania Landlord and Tenant Act, 68 PENN. STAT. §§
250.101 et seq is DISMISSED. Neither IIRA nor RO violate the procedural
protections required under the Landlord and Tenant Act.
Count VIII, privacy rights, is DISMISSED. We lack sufficient
evidence to make a determination with regard to plaintiffs’ privacy rights.
Count IX, police powers, we find FOR PLAINTIFFS. Enacting
unconstitutional laws is beyond the defendant’s police powers

So, among other components of this decision, Munley finds that the IIRA and RO violate due process, pre-empt federal law, and unduly interfere with certain rights to contract, and, thus, the police lack the power to enforce these laws. However, Munley does not find that the IIRA or RO discriminate on the basis of race (violate equal protection) or violate privacy rights.

The city of Hazleton says that it will appeal this decision.

[Corrected my summary of what violations Munley found.]