MK Danny Danon (Likud) is proposing a bill that would require any organization which petitions the Israeli Supreme Court to simultaneously supply the court with a list of their donors from the past 3 years.

YNet reports the details of this interesting bill:

The bill was proposed as an amendment to Basic Law: The Judiciary. It states that the High Court will only accept petitions making claims in the name of organizations based in Israel and operating mainly in the Jewish state.

It also states that just one petition at a time can be filed in the name of the injured party, and that it must be related to a fundamental infringement of basic state order, a fundamental flaw in the operations of the civil administration against the public, or any matter of an outstanding public nature.

...any organization petitioning the High Court will have to present the court with a list of all donations and funds it has received in the past three years. The organization will have to outline the identity of the donor as well as the sum and aim of the funds.

This law sounds quite fair and balanced to me. It doesn't target any group specifically. It sets down reasonable ground rules regarding who can petition the Supreme Court and why.

Yet for some reason the Left is already up in arms claiming that this law targets them.

So let's examine that claim.

The organizations must be Israel based and work primarily in Israel.
I would assume if an organization claims to be an Israeli organization, then shouldn't it meet these qualifications?

I can imagine if Green Peace wanted to petition Israel, then it would have to be the Israeli offices of Green Peace that do it.

So why would this threaten Leftwing organizations in Israel?

just one petition at a time can be filed in the name of the injured party
This is actually a two-parter. First of all, that means no throwing petition after petition at the Supreme Court simultaneously in order to hope one sticks.

Is this a tactic the Left regularly uses that will be blocked?

Second, it requires there actually be an injured party.

Certainly an interested party needs to be required (it didn't use to be that way, and any Leftwing group would bring a petition, but now they have to typically find an Arab who claims to have been affected (an interested party), if I understand this correctly, it actually requires for there to be an injured party, not just an interested one.

Is this a tactic the Left uses that will be blocked?

a list of all donations and funds...
Shouldn't the judges have all the information at hand as to who is behind the petition? Is it really the petitioner and an Israeli organization? Or perhaps it is a foreign government trying to interfere in Israeli politics working through a shell organization.

Would exposure of this knowledge be detrimental to the way the Israeli Left works?

Assuming these answers are 'yes', it's clear why these Leftist organizations are afraid of this bill, it would expose them for what they really are, and block their attempts to alter Israeli democracy through non-democratic means.