Please help.

Can anyone give me a couple of examples of political activites that the union can pursue to manipulate the firm's elasticity of labor demand using Marshalls rules of derived demand.

Unions have been effective in affecting legislation regarding:

1) worker safety
2) worker conditions
3) number of workable hours in a week
4) notification requirement before layoffs
5) minimum wages
6) etc.

Each of these has an impact on the level and elasticity in the demand for labor.