Walker's opponents said his true intent was not to balance the budget but to quash public unions, a strong political force typically for Democrats.
The lawsuit points out that the two groups exempted from the law — state troopers and inspectors — are represented for lobbying purposes by the Wisconsin Troopers Association, which endorsed Walker in the 2010 election. All other law enforcement groups represented by WLEA that did not endorse a candidate in the 2010 election were covered by the law.
The lawsuit said the law forced the WLEA to break into two parts, each with different rights.
The law was designed to retaliate against law enforcement WLEA members and restrict free speech rights "for the improper purpose of diminishing the law enforcement unions' political effectiveness," the lawsuit argues.
The lawsuit also contends that constitutional equal protection rights were violated by treating those represented by the WLEA differently than similarly situated employees.
The WLEA said in a statement that the law "fractured the union and the solidarity of its members, undermining their ability to join together and advocate for the best conditions to keep Wisconsin roads and communities safe."