SimpleDateFormat (used by the default Converter, extended by Seam Converter) accepts a 2 digits year, even if the patter is set to a 4 digits year, so entering 27/10/45 was translated to 27/10/0045 by the Converter. My simple fix was to ensure the Date was between 1800 and 2100 (I could also throw an Exception if a regexp pattern was not matched…

CustomDateConverter.java

package com.domiserve.servidom.util;

import java.util.Calendar;
import java.util.Date;

import javax.faces.application.FacesMessage;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.convert.ConverterException;

import org.jboss.seam.annotations.Name;
import org.jboss.seam.annotations.faces.Converter;
import org.jboss.seam.annotations.intercept.BypassInterceptors;
import org.jboss.seam.ui.converter.DateTimeConverter;

@Converter(forClass = Date.class)
@Name(value = "org.jboss.seam.faces.dateConverter")
@BypassInterceptors
public class CustomDateConverter extends DateTimeConverter {
  private static String DATE_PATTERN = "dd/MM/yyyy";

	public CustomDateConverter() {
		setPattern(DATE_PATTERN);
	}

	@Override
	public Object getAsObject(FacesContext context, UIComponent component,
			String value) {
		Date d = (Date) super.getAsObject(context, component, value);

		Calendar c = Calendar.getInstance();
		c.clear();
		c.set(Calendar.YEAR, 1800);
		Date dateMin = c.getTime();
		c.set(Calendar.YEAR, 2100);
		Date dateMax = c.getTime();

		if (d != null && (d.before(dateMin) || d.after(dateMax))) {
			// interdit de saisir des dates avant 1800 et après 2100
			FacesMessage message = new FacesMessage();
			message.setSummary("Année invalide (format AAAA, entre 1800 et 2100)");
			message.setSeverity(FacesMessage.SEVERITY_ERROR);
			throw new ConverterException(message);
		}

		return d;
	}

	@Override
	public String getAsString(FacesContext context, UIComponent component,
			Object value) {
		return super.getAsString(context, component, value);
	}

}