I'm almost sure it is 6 months form the application not the offence but I can't find the exact reference at the moment. On this basis you must show up.
It is clear from this (DPP (at the suit of Sergeant Emmett Treacy) v Thomas [2006] IEHC 284 ) that the complaint should be issued within 6 months of the alledged offence not the summons. The 1851 and the 1986 Act are the relevant ones.
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The relevant earlier statutory provision is s. 10(4) of the Act of 1851, which provides inter alia that:-
“In all cases under summary jurisdiction the complaint shall be made…within six months from the time when the cause of complaint shall have arisen but not otherwise.”
The general rule is that, where summary offences are alleged, an application for a summons pursuant to the Act of 1986 must be made within six months from the date of the commission of the offence alleged. In DPP v. Roche and Kelly [1990] 2 I.R. 526, the Supreme Court at p. 527 (confirmed that):-
“The effect of s. 1 subs. 7(a) of the Act of 1986 was to apply the six month time limit from the date of the alleged offences as provided by s. 10(4) of the Act of 1851 to the date of application for the summons.”
Also I have learned by PM from Patt that the offence was in December and the complaint was made in April with the summons being issued in June. Based on that the complaint is valid as it is made within the six month period.