What made it difficult for Mexican Americans to win court cases against Anglo Americans who laid claim to their land?

The burden of proof was put on Mexican Americans to prove that they owned the land.

Hope this is the right answer because Mexicans couldn't prove much.

The burden of proof was put on Mexican Americans to prove that they owned the land.

Explanation:

What made it very difficult for Mexican Americans to win lawsuits against Anglo-Americans claiming their lands was the fact that the courts responsible for these lawsuits did not act impartially and always tried to ease the Anglo-American side. That's because the courts used legal evidence guidelines based on US law and that was very damaging to Mexican Americans.