"The Law looks out for those who look out for themselves"

"The Law looks out for those who look out for themselves" - this is the phrase in question. What is the meaning, is this an idiom or well known expression?
I would appreciate any input on this phrase you can give me.

The law tends to support those who defend their rights in some areas. For instance, if you do nothing to protect your own copyright, then the courts will looks less favourably on you than they would on someone who had tried to protect it before going to the courts. If you let me taks a shortcut through your garden for a long time and then tell me to get out, they might interpret your not claiming your rights as allowing me the right to cut across your lawn. ;-)

Thank you. Do you know any resources on the web where I can read more on this subject?

This is an adaptation of a famous saying:

"God helps those who help themselves." The author is Algernon Sidney (1622-1683) from his work Discourses on Government.

Sidney probably adapted a saying from Sophocles (496-406 B.C.) "Heaven never helps the men who will not act."

I found these quotations at bartleby.com. It's one of my favorite sites for literary facts.

Tdol is, as usual, correct in his interpretation of the saying. The general theme here is one of self-reliance.