I s'pose derecha is the only one in the feminine form to separate it from the sense of 'law' / 'right'.
On that note, I always found it interesting that Spanish and English (and others) have the same word for the direction right (derecho/a) and e.g. human rights (derechos humanos). It's a very interesting etymological journey that connects the two very different meanings.
Start with the Proto-Indo-European of [reg] meaning to move in a straight line. This evolved not only into a lot of words for "straight" (Eng: di[rec]t, Sp: de[rec]ho, etc.) but also what is morally cor[rec]t (really it went through Latin first but...). So here we get right as "correct".
Since early Christians saw the right (as in direction) as good and the left ("sinistra" in Latin) as bad (à la Jesus separating the lambs to the right and the goats to the left). Also, with most people being right-handed, left-handedness was a mark of the Devil (leading "sinistra" --> "sinister" as in bad), the "morally correct" hand became the right hand.
Since people saw "rights" as things they were morally obligated to, it became "right" to give "rights". (think Bill of Rights = Bill of *what is right*).
Other fun words with the same root: rectum, surrogate, interrogate, rogue, and erect!
Turns out, it's almost the same...