There was a sign on the grass instructing people not to walk on it : http://tinyurl.com/2p76dh
The law firm decided that they would commit their time and staff to the law suit.
Student or Learner
There was a 'keep off the grass' sign.
A leading law firm took up his case.
Please explain the highlighed expressions.
I couldn't understand this expression of yours.The law firm decided that they would commit their time and staff to the law suit.
If you have a legal difficulty, you ask a law firm to take on your case - they will do the research into the circumstances of the problem, and will represent you by writing letters on your behalf or in a court of law.
They must decide first if it going to be financially rewarding to the company as people's time will be spent doing the work and if the case fails, there may be no money to pay them.
More context for your sentence would help.