Supreme Court has struck down the Section 8(4) as ultra vires to the Constitution which was in the following fashion,

(4) Notwithstanding anything in sub-section (1), sub-section (2) and sub-section (3) a disqualification under either sub-section shall not, in the case of a person who on the date of the conviction is a member of Parliament or the Legislature of a State, take effect until three months have elapsed from that date or, if within that period an appeal or application for revision is brought in respect of the conviction or the sentence, until that appeal or application is disposed of by the court.

From Paras 19 and 20,

19. The result of our aforesaid discussion is that the affirmative words used in Articles 102(1)(e) and 191(1)(e) confer power on Parliament to make one law laying down the same disqualifications for a person who is to be chosen as member of either House of Parliament or as a member of the Legislative Assembly or Legislative Council of a State and for a person who is a sitting member of a House of Parliament or a House of the State Legislature and the words in Articles 101(3)(a) and 190(3)(a) of the Constitution put express limitations on such powers of the Parliament to defer the date on which the disqualifications would have effect. Accordingly, sub-section (4) of Section 8 of the Act which carves out a saving in the case of sitting members of Parliament or State Legislature fromthe disqualifications under sub-sections (1), (2) and (3) of Section 8 of the Act or which defers the date on which thedisqualification will take effect in the case of a sitting member of Parliament or a State Legislature is beyond the powers conferred on Parliament by the Constitution.

20. Looking at the affirmative terms of Articles 102(1)(e) and 191(1)(e) of the Constitution, we hold that Parliament has been vested with the powers to make law laying down the same disqualifications for person to be chosen as a member of Parliament or a State Legislature and for a sitting member of a House of Parliament or a House of a State Legislature. We also hold that the provisions of Article 101(3)(a) and 190(3)(a) of the Constitution expressly prohibitParliament to defer the date from which the disqualification will come into effect in case of a sitting member of Parliament or a State Legislature.Parliament, therefore, has exceeded its powers conferred by the Constitution in enacting sub-section (4) of Section 8 of the Act and accordingly subsection(4) of Section 8 of the Act is ultra vires the Constitution.

From Para 23,

…

Sitting members of Parliament and State Legislature who have already been convicted for any of the offences mentioned in sub-section (1), (2) and (3) of Section 8 of the Act and who have filed appeals or revisions which are pending and are accordingly saved from the disqualifications by virtue of sub-section (4) of Section 8 of the Act should not, in our considered opinion, be affected by the declaration now made by us in this judgment.

…

However, if any sitting member of Parliament or a State Legislature is convicted of any of the offences mentioned in sub-sections (1), (2) and (3) of Section 8 of the Act and by virtue of such conviction and/or sentence suffers the disqualifications mentioned in sub-sections (1), (2) and (3) of Section 8 of the Act after the pronouncement of this judgment, his membership of Parliament or the State Legislature, as the case may be, will not be saved by subsection (4) of Section 8 of the Act which we have by this judgment declared as ultra vires the Constitution notwithstanding that he files the appeal or revision against the conviction and /or sentence.

Lily Thomas Vs Union of India and Ors on 10 Jul 2013

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Citations : [2013 ABR 6 236], [2013 AD SC 10 655], [2013 AIR SC 2662], [2013 AWC SC 6 5458], [2013 BOMCR 5 261], [2013 CGLRW SC 2 339], [2014 CLT SC 117 284], [2013 JLJR 3 351], [2013 JT SC 9 419], [2013 KARLJ 5 1], [2013 KLJ 3 284], [2013 KERLT 3 296], [2013 LW 4 857], [2013 MLJ 5 463], [2013 OLR 2 941], [2013 PLJR 3 261], [2013 RCR CIVIL 3 713], [2013 SCALE 8 469], [2013 SCC 7 653], [2013 SCC L&S 7 811], [2014 WBLR SC 1 69], [2013 SCC CIV 3 678], [2013 SCC CRI 3 641], [2013 SCC L&S 2 811], [2013 SCC ONLINE SC 603], [2013 GUJ LH 2 408], [2013 GUJ LR 3 2209], [2013 ILR KERALA 3 203], [2014 CUT LT 117 284]

Other Sources :

https://indiankanoon.org/doc/63158859/

https://www.casemine.com/judgement/in/5609af2ee4b0149711415be4

Supreme Court Landmark Judgment- Lilly Thomas v. Union of India