The expected compensation for being a Legal Assistant at any law firm, depends on your experience. I remember when I started I was earning $9.50 per hour and within 4 years I was earning double that, and there was still room to grow and increase the salary. How much you earn as a Legal Assistant depends all on you, the more you learn, the more you're worth, the more you get paid.
It can always depend on experience and region. I started with no knowledge and got minimum wage of $12/hr, and in 2 years that had gone up to $20/hr. There will always be multiple factors in play; in my case it was the minimum wage at home and the rate at which my boss decided to give me raises.