There are two parts to this: an opening section on the way that charges of ‘anti-Semitism’ are used to smear and intimidate anyone who is critical of Israel’s policies, and a sustained dissection and attack on Dershowitz’ book ‘The Case for Israel’.
You’ve probably noticed that in recent years television pundits have been leveling charges of antisemitism at critics of Israel. Even if the critics are Jewish; even if they are Israeli citizens; it doesn’t matter. By definition, now, if you criticize Israel you are antisemitic. In other words, AIPAC, the Israel lobby generally, and neo-conservatives have literally redefined antisemitism to mean anyone who is not a cheerleader for Israeli hegemony. In other words, they’ve succeeded in divesting the term of any sensible meaning whatsoever.
I have not read Dershowitz’ book, so I have no way to know whether Finkelstein has demolished it as much as it seems. Finkelstein brings two major charges against Dershowitz: plagiarism (documented in detail in an appendix), and false reporting. Basically Finkelstein shows that Dershowitz makes a great many false claims, and that he bases his information almost entirely on Israeli government sources and apologists for Israel. Finkelstein shows that independent assessors of Israel’s policies in the West Bank and Gaza agree almost universally that Israel has committed many war crimes, and that its occupation of Palestine territory is contrary to international law and convention.
None of this is controversial outside the United States. The UN has voted many times to affirm that Israel must withdraw into the 1967 borders; that the settlements are illegal; that the occupation is illegal. There are typically between 2 and 5 votes in opposition: the US, Israel, and 1 to 3 Pacific island nations that owe their livelihood to the US. But here in the US it is almost impossible to hear serious criticism of Israeli policies in the mainstream media, and Congress seems to be entirely a creature of AIPAC on all questions regarding Israel.